This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A067875 #10 May 24 2016 11:37:18 %S A067875 668,1964,2434,3248,5152,8400 %N A067875 One player's total legal chess moves by piece type on standard chessboard. %C A067875 The terms are given in order of increasing numbers of total moves for the six piece types; that is, a(1) Pawn, a(2) Knight, a(3) King, a(4) Bishop, a(5) Rook and a(6) Queen. %C A067875 The sum of these six terms is 21866, the total number of moves available to White or to Black. Hence 43732 moves, the answer to a question raised in the link below, are available to both players. %C A067875 Notes: (1) Capturing, for example, a Knight on a particular square counts as a different move from capturing, for example, a Rook on the same square. %C A067875 (2) Moving a piece to a square without capturing is counted separately from captures by the piece on that square. %C A067875 (3) The two castling moves are counted as King moves only. %C A067875 (4) The 14 en passant captures are included in the Pawn moves. %C A067875 (5) Two-square initial Pawn moves are included. %C A067875 (6) Pawn promotion on a particular square to a Bishop, for example, counts as a different move from promotion to a Queen on the same square. %C A067875 (7) Pieces of the same type and color are considered indistinguishable. %C A067875 (8) Moves causing check, discovered check, double check, checkmate, or stalemate are not distinguished from other moves. %C A067875 Valid boards and moves require (these two somewhat subtle realizations): %C A067875 (9) A King cannot capture Pawns on their original squares when they would be attacking the King; this would require the King to have made an illegal move earlier by walking into check. %C A067875 (10) A King cannot diagonally capture Bishops on their home corner squares - again this would require the King to have made an illegal move earlier. However, a King can diagonally capture Bishops on the other two corners as the Bishop can be in position *after* the King is - via Pawn promotion in this case. %D A067875 Inspired by a question posed by Tim Krabbé. %H A067875 T. Krabbé, <a href="http://www.xs4all.nl/~timkr/chess2/diary_6.htm">Open Chess Diary, Item 105, Mar 29 2001: Never in a trillion</a> %F A067875 a(6) = a(4) + a(5) (Queen moves equal sum of Bishop and Rook moves). Generalizing all terms for n X n chessboards other than 8 x 8 requires defining how many pieces and how many types of pieces are originally on the board and/or can be promoted to, especially because of the way captures are counted. %Y A067875 Cf. A035005 - A035008, A033586 (count the moves per piece type differently). %K A067875 fini,full,nonn %O A067875 1,1 %A A067875 _Rick L. Shepherd_, Feb 25 2002