A113844 a(1) =a(2) =1. a(n+1) = (sum{1<=k<=n/2} a(k)) * (sum{n/2<j<=n} a(j)).

1, 1, 1, 2, 6, 18, 78, 312, 2070, 12420, 163878, 1966536, 62213526, 1866405780, 206591803854, 22311914816232, 9436063264020024, 3963146570888410080, 9887814229774042889370, 24620657432137366794531300

Offset

1,4

Links

Table of n, a(n) for n=1..20.

Example

a(8) = (a(1)+a(2)+a(3)) * (a(4)+a(5)+a(6)+a(7)) =
(1+1+1) * (2+6+18+78) = 312.

Crossrefs

Sequence in context: A280763 A079391 A162058 * A266858 A141580 A007869

Adjacent sequences: A113841 A113842 A113843 * A113845 A113846 A113847

Keyword

easy,nonn

Author

Leroy Quet, Jan 24 2006

Extensions

More terms from Evonne Haines (avissean(AT)adelphia.net), Jan 28 2006

Status

approved