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 A259099 Triangle read by rows: Kreweras's "Rule A_4 left thickness" numbers. 1
 1, 1, 2, 1, 6, 4, 1, 16, 20, 8, 1, 48, 76, 56, 16, 1, 170, 284, 272, 144, 32, 1, 686, 1128, 1200, 848, 352, 64, 1, 3008, 4808, 5280, 4304, 2432, 832, 128, 1, 13888, 21688, 23904, 20848, 13952, 6592, 1920, 256, 1, 66354, 101912, 111856, 100592, 73952, 42176, 17152, 4352, 512 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Lars Blomberg, Table of n, a(n) for n = 1..210 (the first 20 rows) G. Kreweras, Sur les hiérarchies de segments, Cahiers du Bureau Universitaire de Recherche Opérationnelle, Institut de Statistique, Université de Paris, #20 (1973). See page 25. G. Kreweras, Sur les hiérarchies de segments, Cahiers du Bureau Universitaire de Recherche Opérationnelle, Institut de Statistique, Université de Paris, #20 (1973). (Annotated scanned copy) FORMULA Kreweras gives a recurrence on page 24. EXAMPLE Triangle begins:   1;   1,   2;   1,   6,   4;   1,  16,  20,   8;   1,  48,  76,  56,  16;   1, 170, 284, 272, 144,  32;   1, 686, 1128, 1200, 848, 352, 64;   1, 3008, 4808, 5280, 4304, 2432, 832, 128;   1, 13888, 21688, 23904, 20848, 13952, 6592, 1920, 256;   1, 66354, 101912, 111856, 100592, 73952, 42176, 17152, 4352, 512;   ... CROSSREFS Sequence in context: A269479 A118040 A073387 * A125693 A094527 A054335 Adjacent sequences:  A259096 A259097 A259098 * A259100 A259101 A259102 KEYWORD nonn,tabl AUTHOR N. J. A. Sloane, Jun 22 2015 EXTENSIONS More terms from Lars Blomberg, Apr 28 2019 STATUS approved

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Last modified August 24 17:01 EDT 2019. Contains 326295 sequences. (Running on oeis4.)