A030033 a(n+1) = Sum_{k = 0..floor(2*n/3)} a(k)*a(n-k) for n >= 0 with a(0) = 1.

1, 1, 1, 2, 4, 7, 15, 34, 72, 165, 387, 861, 2039, 4894, 11256, 27085, 66021, 156347, 381720, 940211, 2261208, 5578659, 13846756, 33654950, 83539418, 208608556, 512069441, 1278522424, 3207377196, 7925966000

Offset

0,4

Links

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Maple

a := proc(n) local k; option remember;
     if n = 0 then 1;
     else add(a(k)*a(n - 1 - k), k = 0 .. floor(2/3*n - 2/3));
     end if;
end proc;
seq(a(n), n = 0..30); # Petros Hadjicostas, Nov 07 2019

Crossrefs

Cf. A000992, A030032, A030037.

Sequence in context: A358824 A072964 A247291 * A364596 A280031 A135131

Adjacent sequences: A030030 A030031 A030032 * A030034 A030035 A030036

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Name edited by Petros Hadjicostas, Nov 07 2019

Status

approved