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 A243716 Irregular triangle read by rows: T(n, k) = number of inequivalent (mod the dihedral group D_8 of order 8) ways to place k nonattacking knights on an n X n board. 6
 1, 1, 2, 1, 1, 3, 7, 9, 6, 2, 3, 18, 40, 66, 49, 30, 8, 3, 6, 43, 195, 609, 1244, 1767, 1710, 1148, 510, 154, 31, 6, 1, 6, 83, 618, 3375, 12329, 32524, 61731, 86748, 90059, 70128, 40770, 18053, 6089, 1643, 344, 61, 7, 1, 10, 156, 1751, 14181, 81900, 348541 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS The triangle is irregularly shaped: 1 <= k <= A030978(n). A030978(n) is the maximal number of knights that can be placed on an n X n board. First row corresponds to n = 1. Counting "inequivalent ways" means: Rotations or reflections of a placement of knights on the board are considered to be the same placement. LINKS Heinrich Ludwig, Table of n, a(n) for n = 1..116 EXAMPLE The triangle begins: 1; 1, 2, 1, 1; 3, 7, 9, 6, 2; 3, 18, 40, 66, 49, 30, 8, 3; 6, 43, 195, 609, 1244, 1767, 1710, 1148, 510, 154, 31, 6, 1; ... CROSSREFS Cf. A030978, A008805 (column 1), A243717 (column 2), A243718 (column 3), A243719 (column 4), A243720 (column 5). Sequence in context: A361707 A135701 A051467 * A356776 A333988 A195805 Adjacent sequences: A243713 A243714 A243715 * A243717 A243718 A243719 KEYWORD nonn,tabf AUTHOR Heinrich Ludwig, Jun 10 2014 STATUS approved

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Last modified December 3 02:48 EST 2023. Contains 367530 sequences. (Running on oeis4.)