A173099 a(1)=1, a(2)=3, a(n)=2*a(n-2)*a(n-1)-a(n-2)-a(n-1).

1, 3, 2, 7, 19, 240, 8861, 4244179, 75211087198, 638418558490509507, 96032307742263928939148386067, 122617614954666266094919182714589930973500782364

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Mathematica

a=1; b=3; lst={a, b}; Do[c=2*a*b-a-b; AppendTo[lst, c]; a=b; b=c, {n, 12}]; lst
nxt[{a_, b_}]:={b, 2*a*b-a-b}; NestList[nxt, {1, 3}, 12][[All, 1]] (* Harvey P. Dale, Jan 03 2022 *)

Crossrefs

Cf. A173093, A173094, A173096, A173097, A173098

Sequence in context: A177115 A316087 A196537 * A111928 A348695 A248054

Adjacent sequences: A173096 A173097 A173098 * A173100 A173101 A173102

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Feb 09 2010

Status

approved