A337187 a(n) = 1 + Sum_{k=0..n-2} binomial(n-2,k) * a(k) * a(n-k-2).

1, 1, 2, 3, 7, 19, 63, 229, 955, 4407, 22445, 124249, 746003, 4821287, 33394193, 246652725, 1935828995, 16086138151, 141100295557, 1302780182449, 12630092274099, 128275445380247, 1362029496267529, 15090795795916493, 174167341456580947, 2090520625244752407

Offset

0,3

Links

Table of n, a(n) for n=0..25.

Formula

E.g.f. A(x) satisfies: A''(x) = exp(x) + A(x)^2.

Mathematica

a[n_] := a[n] = 1 + Sum[Binomial[n - 2, k] a[k] a[n - k - 2], {k, 0, n - 2}]; Table[a[n], {n, 0, 25}]

Crossrefs

Cf. A007558, A054687, A090344.

Sequence in context: A005807 A167422 A060276 * A358049 A025563 A336296

Adjacent sequences: A337184 A337185 A337186 * A337188 A337189 A337190

Keyword

nonn

Author

Ilya Gutkovskiy, Jan 29 2021

Status

approved