A375608 Expansion of e.g.f. 1 / (exp(x^2) - x).
1, 1, 0, -6, -36, -120, 240, 8400, 82320, 362880, -3507840, -103783680, -1268688960, -4843238400, 175429013760, 5052189542400, 68016191443200, 55329155481600, -23284682272051200, -668640423164313600, -9013925405784499200, 57340797108269875200
Offset: 0
Keywords
Programs
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PARI
my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(exp(x^2)-x))) -
PARI
a(n) = n!*sum(k=0, n\2, (-n+2*k-1)^k/k!);
Formula
a(n) = n! * Sum_{k=0..floor(n/2)} (-n+2*k-1)^k/k!.