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A121810
a(n) = a(n - 1)*a(n - 2) + a(n - 2)*a(n - 3) + a(n - 1)*a(n - 3).
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]
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}]
nxt[{a_, b_, c_}]:={b, c, a*b+b*c+a*c}; NestList[nxt, {1, 1, 0}, 20][[;; , 1]] (* Harvey P. Dale, Aug 29 2024 *)
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
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