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 A131413 A002024 + A128076 - A000012. 1
 1, 4, 3, 7, 6, 3, 10, 9, 8, 7, 13, 12, 11, 10, 9, 16, 15, 14, 13, 12, 11, 19, 18, 17, 16, 15, 14, 13, 22, 21, 10, 19, 18, 17, 16, 15, 25, 24, 23, 22, 21, 20, 19, 18, 17, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Row sums = A000566, the heptagonal numbers: (1, 7, 18, 34, 55,...). LINKS FORMULA A002024 + A128076 - A000012 as infinite lower triangular matrices. By rows, (n+1) terms of 3n+1, 3n, 3n-1,... EXAMPLE First few rows of the triangle are: 1; 4, 3; 7, 6, 5; 10, 9, 8, 7; 13, 12, 11, 10, 9; 16, 15, 14, 13, 12, 11; 19, 18, 17, 16, 15, 14, 13; ... CROSSREFS Cf. A128076, A002024, A000566. Sequence in context: A093051 A089020 A046560 * A205392 A249189 A168200 Adjacent sequences:  A131410 A131411 A131412 * A131414 A131415 A131416 KEYWORD nonn,tabl AUTHOR Gary W. Adamson, Jul 08 2007 STATUS approved

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Last modified May 25 17:36 EDT 2020. Contains 334595 sequences. (Running on oeis4.)