A348530 a(1) = 1; a(n) = Sum_{k=1..ceiling(n/2)} a(k) * a(n-k).

1, 1, 2, 3, 7, 14, 33, 70, 173, 400, 1008, 2391, 6132, 15019, 38799, 96520, 252022, 638788, 1679091, 4297452, 11373921, 29426350, 78204705, 203658812, 543828898, 1426912159, 3822817135, 10078227662, 27092960887, 71803114869, 193496832857, 514684042158

Offset: 1

Author

Ilya Gutkovskiy, Oct 21 2021

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..2238

Crossrefs

Cf. A000108, A000992.

Programs

Maple

a:= proc(n) option remember; `if`(n=1, 1,
      add(a(k)*a(n-k), k=1..ceil(n/2)))
    end:
seq(a(n), n=1..32);  # Alois P. Heinz, Oct 21 2021

Mathematica

a[1] = 1; a[n_] := a[n] = Sum[a[k] a[n - k], {k, 1, Ceiling[n/2]}]; Table[a[n], {n, 1, 32}]