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 A244519 Expansion of Product_{n>=1} (1 + H(x^n)) where H(x) is the g.f. of A000081. 1
 1, 1, 2, 4, 8, 16, 35, 76, 175, 414, 1009, 2510, 6382, 16448, 42961, 113352, 301715, 808932, 2182739, 5921803, 16143975, 44199809, 121477237, 335015538, 926814691, 2571322157, 7152404733, 19942874638, 55729271645, 156051344975, 437801148097, 1230423785329, 3463777894236, 9766002585763, 27574869734583, 77965430442158 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Which combinatorial objects does this sequence count? LINKS Joerg Arndt, Table of n, a(n) for n = 0..500 PROG (PARI) N=66; A=vector(N+1, j, 1); for (n=1, N, A[n+1] = 1/n * sum(k=1, n, sumdiv(k, d, d * A[d]) * A[n-k+1] ) ); A000081=concat([0], A); H(t)=subst(Ser(A000081, 't), 't, t); x='x+O('x^N); T=prod(n=1, N, 1 + H(x^n)); Vec(T) CROSSREFS Cf. A001372 (expansion of 1/Product_{n>=1} (1 - H(x^n))). Sequence in context: A180207 A013025 A034339 * A247293 A337716 A126137 Adjacent sequences: A244516 A244517 A244518 * A244520 A244521 A244522 KEYWORD nonn AUTHOR Joerg Arndt, Jul 10 2014 STATUS approved

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Last modified September 26 08:38 EDT 2023. Contains 365654 sequences. (Running on oeis4.)