english - A Quindectet of Letter Sequences!

I've been working hard on trying to solve the missing letters in this puzzle by qwertylpc, but I've discovered that in trying to figure out the lists his clues are coming from, I've come up with several lists of my own! Since I am stumped on the last two clues in his puzzle, I'm going to dump all of the clues I've thought of into this puzzle!

EASY
1) P, N, D, ?
2) P, K, B, R, ?
3) F, C, G, D, ?

4) B, K, M, G, ?

MEDIUM
5) B, G, B, G, R, ?
6) G, E, L, N, D, J, J, ?
7) T, T, C, P, Q, ?
8) H, O, T, T, S, F, ?
9) W, J, L, H, J, G, ?

HARD
10) E, F, W, W, ?
11) L, G, G, S, W, E, ?

12) P, T, F, C, G, G, ?
13) M, J, P, L, S, D, H, ?
14) S, C, P, G, O, ?

VERY HARD
15) L, H, H, B, S, B, B, ?

Important information:

• Note the english tag. Also, many of these are US-centric, including one that would have a slightly different sequence in Britain.


• All of the letters come from ordered lists of things. So you don't have to worry about how the letters look (e.g. A, E, F, H, I, ? is "K" because no curved lines in the capital letters), or their position in the alphabet (no need to do math or anything).


• All of the answers are the first letter of a word, but not necessarily from the first word in a phrase/name. So if the sequence is Neil Armstrong, Buzz Aldrin, Pete Conrad, I wouldn't give you "E, U, E" or "G, N, D" but I could just as easily give you "A, A, C" as "N, B, P".



• Difficulty groupings are based on my best guess. I suspect some will be easier than I thought, and possibly some will be harder than I thought, but I thought I'd at least make an attempt to classify them.

I would like to avoid giving ANY hints on this puzzle if possible, but I guess we'll see how it goes, particularly with the last one. I'm already thinking of other sequences, so maybe I'll make a sequel!

Edit: Bounty added! In addition to the regular bounty, I'll give another 50 points to whoever solves the VERY HARD sequence (#15), so even if you can only solve that one, go ahead and make your own answer!

Answer

COPIED OVER FROM JOE Z'S ANSWER (#1 to #6)

1. Q. This is the order of the value of U.S. coins (Penny, Nickel, Dime). The next one is Quarter.

2. Q. This the order of the value ranks of chess pieces (Pawn, Knight, Bishop, Rook). The next one is Queen.

3. A. This is the order of sharps in Western key signature notation (F, C, G, D, A, E, B). It's also the initials of the mnemonic "Father Charles Goes Down And Ends Battle".

4. T. This is the order of SI prefixes being applied to bytes (Bytes, Kilobytes, Megabytes, Gigabytes). The next one is Terabytes.

5. J. This is the order of the first names of United States Presidents from Obama going backwards (Barack, George, Bill, George, Ronald). The next one is Jimmy Carter.

6. R. This is the order of the books of the Old Testament in the Bible (Genesis, Exodus, Leviticus, Numbers, Deuteronomy, Joshua, Judges). The next one is Ruth.

ANSWERS FROM OTHERS (#7, #9, #14)

7. G. Teaspoon, Tablespoon, Cup, Pint, Quart, Gallon. (From Bailey M.)

9. F. Faces on US paper currency: Washington, Jefferson, Lincoln, Hamilton, Jackson, Grant, Franklin. (From dennisdeems)

14. H. The Harry Potter series: Sorcerer's Stone, Chamber of Secrets, Prisoner of Azkaban, Goblet of Fire, Order of the Phoenix, Half-Blood Prince
(outside of the US, the first name is Philosopher's Stone) (From GordonK)

LEN'S ANSWERS

8) H, O, T, T, S, F, ?

Poker hand ranking:
High card, One pair, Two pair, Three of a kind, Straight, Flush, Full house . . .

10) E, F, W, W, ?

The five powers in Captain Planet and the Planeteers (animated TV series):

Earth, Fire, Wind, Water, Heart

11) L, G, G, S, W, E, ?

The seven deadly sins, in the order used by Pope Gregory I:
Lust, Gluttony, Greed, Sloth, Wrath, Envy, Pride

12) P, T, F, C, G, G, ?

"The Twelve Days of Christmas" song:

a Partridge, two Turtle doves, three French hens, four Calling birds, five Gold rings, six Geese a-laying, seven Swans a-swimming . . .

13) M, J, P, L, S, D, H, ?

US state capitals ordered by the alphabetical state names:
Montgomery Alabama, Juneau Alaska, Phoenix Arizona, Little Rock Arkansas, Sacramento California, Denver Colorado, Hartford Connecticut, Dover Delaware . . .

15) L, H, H, B, S, B, B, ?

The twelve labours of Hercules:

Nemean Lion, Lernaean Hydra, Ceryneian Hind, Erymanthian Boar, Augean Stables, Stymphalian Birds, Cretan Bull, Mares of Diomedes . . .