A091957 a(1)=0, a(2)=1, a(n)=A000217(a(n-1)) + A000217(a(n-2)).

0, 1, 1, 2, 4, 13, 101, 5242, 13747054, 94490767454888, 4464252567107002358694986701, 9964775491460730298984873909049635615687553262572198767

Offset

1,4

Links

Table of n, a(n) for n=1..12.

Prog

(PARI) t(n)=n*(n+1)/2 v=vector(12) v[2]=1 for (i=3, 12, v[i]=t(v[i-1])+t(v[i-2])) v

Crossrefs

Sequence in context: A103845 A055463 A369313 * A327443 A376062 A056678

Adjacent sequences: A091954 A091955 A091956 * A091958 A091959 A091960

Keyword

nonn

Author

Jon Perry, Mar 13 2004

Status

approved