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 A177480 Suppose e
 1, 1, 2, 6, 20, 84, 412, 2300, 14676, 104536, 825660, 7168860, 67826340, 695174208, 7671602644, 90700227700, 1143825611348 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Table of n, a(n) for n=0..16. S. Kitaev, Introduction to partially ordered patterns, Discrete Applied Mathematics 155 (2007), 929-944. MATHEMATICA ok[{e_, f_, g_, h_}] := e > g || e > h || f > g || f > h; a[n_] := Length@ Select[ Permutations[Range@n], AllTrue[ Partition[#, 4, 1], ok] &]; a /@ Range[0, 9] (* Giovanni Resta, Mar 11 2020 *) CROSSREFS Cf. A117156, A177470, A177471, A177472, A177473, A177474, A177475, A177476, A177477, A177478, A177479, A177481, A177482, A177483, A177484. Sequence in context: A266600 A177474 A372987 * A365229 A089179 A177483 Adjacent sequences: A177477 A177478 A177479 * A177481 A177482 A177483 KEYWORD nonn,more AUTHOR Signy Olafsdottir (signy06(AT)ru.is), May 09 2010 EXTENSIONS a(0), a(10)-a(14) from Alois P. Heinz, Mar 10 2020 a(15)-a(16) from Giovanni Resta, Mar 11 2020 STATUS approved

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Last modified September 16 14:46 EDT 2024. Contains 375976 sequences. (Running on oeis4.)