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

Author

Vladimir Joseph Stephan Orlovsky, Feb 09 2010

Keywords

• nonn

Crossrefs

Cf. A173093, A173094, A173096, A173097, A173098

Programs

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 *)