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
Keywords
Programs
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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 *)