A363470 G.f. satisfies A(x) = exp( 2 * Sum_{k>=1} A(-x^k) * x^k/k ).
1, 2, -1, -6, 7, 42, -58, -366, 513, 3406, -4846, -33310, 48304, 339446, -499133, -3565468, 5294439, 38312242, -57332347, -419177900, 631252549, 4654229300, -7045498256, -52310262192, 79531957334, 593986308994, -906439292326, -6803984285256
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..1000
Programs
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PARI
seq(n) = my(A=1); for(i=1, n, A=exp(2*sum(k=1, i, subst(A, x, -x^k)*x^k/k)+x*O(x^n))); Vec(A);
Formula
A(x) = B(x)^2 where B(x) is the g.f. of A200438.
A(x) = Sum_{k>=0} a(k) * x^k = 1/Product_{k>=0} (1-x^(k+1))^(2 * (-1)^k * a(k)).
a(0) = 1; a(n) = (2/n) * Sum_{k=1..n} ( Sum_{d|k} d * (-1)^(d-1) * a(d-1) ) * a(n-k).