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A121810
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a(n) = a(n - 1)*a(n - 2) + a(n - 2)*a(n - 3) + a(n - 1)*a(n - 3).
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3
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1, 1, 0, 1, 1, 1, 3, 7, 31, 331, 12795, 4642051, 60935796571, 283646808320375611, 17285560913056915909539455163, 4902995236325455290013100337511909917402705547
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OFFSET
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-1,7
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COMMENTS
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LINKS
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MATHEMATICA
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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 *)
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PROG
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(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
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CROSSREFS
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Cf. A203761 and references therein.
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KEYWORD
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nonn,changed
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AUTHOR
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EXTENSIONS
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Extended the sequence by prefixing the two values a(0)=a(-1)=1. - M. F. Hasler, Jan 01 2013
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STATUS
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approved
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