A113845 a(1) = a(2) = 1. a(n+1) = (Product_{k=1..floor(n/2)} a(k)) + (Product_{j=ceiling((n+1)/2)..n} a(j)).

1, 1, 2, 3, 7, 43, 905, 817217, 222613996891, 49556991610450473684541, 350842202496894090472936261713260177362896247, 123090251052871637971528096077183553457511351225922468278558723122652153910477674845042677

Offset

1,3

Comments

a(13) has 177 digits. - Emeric Deutsch, Feb 06 2006

Links

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

Example

(1*1*2) + (3*8*50*1202) = 1442402.
a(8) = (a(1)*a(2)*a(3)) + (a(4)*a(5)*a(6)*a(7)) = (1*1*2) + (3*7*43*905) = 817217.

Maple

a[1]:=1: a[2]:=1: for n from 2 to 12 do a[n+1]:=product(a[k], k=1..floor(n/2))+product(a[j], j=1+floor(n/2)..n) od:seq(a[n], n=1..12); # Emeric Deutsch, Feb 06 2006

Crossrefs

Sequence in context: A072714 A051786 A133400 * A072713 A000058 A129871

Adjacent sequences: A113842 A113843 A113844 * A113846 A113847 A113848

Keyword

easy,nonn

Author

Leroy Quet, Jan 24 2006

Extensions

Corrected and extended by Emeric Deutsch, Feb 06 2006

Status

approved