A373525 Expansion of e.g.f. exp(x * (1 + x^4)^(1/2)).
1, 1, 1, 1, 1, 61, 361, 1261, 3361, -37799, 15121, 2522521, 20005921, 486563221, 363363001, -12486293819, 3113772481, -12960051533519, 8909829442081, 528011239172401, 241435513794241, 1381310884267333741, 3097715443570441, -49080307628073705059
Offset: 0
Keywords
Programs
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PARI
a(n) = n!*sum(k=0, n\4, binomial(n/2-2*k, k)/(n-4*k)!);
Formula
a(n) = n! * Sum_{k=0..floor(n/4)} binomial(n/2-2*k,k)/(n-4*k)!.
a(n) == 1 mod 60.