A111236 a(1)=a(2)=a(3)=a(4)=1. For n >= 5, a(n)= (a(n-1)+a(n-2)) * (a(n-3)+a(n-4)).

1, 1, 1, 1, 4, 10, 28, 190, 3052, 123196, 27522064, 89625932920, 11318569384820032, 312907271203608153807520, 28053218967767813941001154374119168, 317524819653692484884273872549799784105586335582976

Offset

1,5

Links

Table of n, a(n) for n=1..16.

Mathematica

RecurrenceTable[{a[1]==a[2]==a[3]==a[4]==1, a[n]==(a[n-1]+a[n-2]) (a[n-3]+ a[n-4])}, a[n], {n, 20}](* Harvey P. Dale, Aug 08 2011 *)

Prog

(PARI) a(n)=if(n<5, 1, (a(n-1)+a(n-2)) *(a(n-3)+a(n-4))) (Klasen)

Crossrefs

Sequence in context: A243600 A239577 A008995 * A164361 A006907 A305204

Adjacent sequences: A111233 A111234 A111235 * A111237 A111238 A111239

Keyword

easy,nonn

Author

Leroy Quet, Oct 28 2005

Extensions

More terms from Lambert Klasen (lambert.klasen(AT)gmx.net), Oct 31 2005

Status

approved