A063404 a(0)=1; a(1)=1; a(2)=1; a(n) = a(n-1) + (1 + a(n-2))*(1 + a(n-3)).

1, 1, 1, 5, 9, 21, 81, 301, 2105, 26869, 662881, 57251101, 17868890441, 37968593886405, 1023051637915653489, 678457667444617722784941, 38843832843299593293720040241881, 694097227974493731990570304927658701989461

Offset

0,4

Links

Harry J. Smith, Table of n, a(n) for n = 0..28

Mathematica

RecurrenceTable[{a[0]==a[1]==a[2]==1, a[n]==a[n-1]+(1+a[n-2])(1+ a[n-3])}, a, {n, 20}] (* Harvey P. Dale, Feb 27 2012 *)

Prog

(PARI) { a=a3=a2=a1=1; for (n = 0, 28, if (n>2, a=a1 + (1 + a2)*(1 + a3); a3=a2; a2=a1; a1=a); write("b063404.txt", n, " ", a) ) } \\ Harry J. Smith, Aug 20 2009

Crossrefs

Sequence in context: A146932 A146476 A110200 * A102177 A375238 A299266

Adjacent sequences: A063401 A063402 A063403 * A063405 A063406 A063407

Keyword

nonn,easy

Author

Olivier Gérard, Jul 16 2001

Extensions

One additional term from Harvey P. Dale, Feb 27 2012

Status

approved