A121810 a(n) = a(n - 1)*a(n - 2) + a(n - 2)*a(n - 3) + a(n - 1)*a(n - 3).

1, 1, 0, 1, 1, 1, 3, 7, 31, 331, 12795, 4642051, 60935796571, 283646808320375611, 17285560913056915909539455163, 4902995236325455290013100337511909917402705547

Offset

-1,7

Comments

Essentially the same as A074047. [R. J. Mathar, Aug 07 2008]

Links

Table of n, a(n) for n=-1..14.

Mathematica

a[0] = 0; a[1] = 1; a[2] = 1; a[n_] := a[n] = a[n - 1]*a[n - 2] + a[n - 2]*a[n - 3] + a[n - 1]*a[n - 3] Table[a[n], {n, 0, 15}]

Prog

(PARI) {f23(x, y, z)=x*y+y*z+z*x; a=[0, 1, 1]; for(n=1, 19, a=concat(a, f23(a[n], a[n+1], a[n+2]))); a} \\ M. F. Hasler, Jan 01 2013

Crossrefs

Cf. A203761 and references therein.

Cf. A074047.

Sequence in context: A277028 A156895 A074047 * A081475 A123212 A213437

Adjacent sequences: A121807 A121808 A121809 * A121811 A121812 A121813

Keyword

nonn

Author

Roger L. Bagula, Aug 30 2006

Extensions

Edited by N. J. A. Sloane, Oct 08 2006

Extended the sequence by prefixing the two values a(0)=a(-1)=1. - M. F. Hasler, Jan 01 2013

Status

approved