A331519 a(0) = 1; a(n) = Sum_{k=1..n} (binomial(n,k) mod 2) * a(k-1) * a(n-k).

1, 1, 1, 3, 3, 9, 15, 63, 63, 189, 315, 1323, 1701, 6237, 12285, 59535, 59535, 178605, 297675, 1250235, 1607445, 5893965, 11609325, 56260575, 63761985, 213790185, 393824025, 1811590515, 2531725875, 10025634465, 21210236775, 109876902975, 109876902975, 329630708925

Offset

0,4

Links

Table of n, a(n) for n=0..33.

Mathematica

a[0] = 1; a[n_] := a[n] = Sum[Mod[Binomial[n, k], 2] a[k - 1] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 33}]

Crossrefs

Cf. A000108, A001147, A047749, A047999, A062177, A166966.

Sequence in context: A062510 A000200 A100744 * A285883 A232948 A241357

Adjacent sequences: A331516 A331517 A331518 * A331520 A331521 A331522

Keyword

nonn

Author

Ilya Gutkovskiy, Jan 19 2020

Status

approved