A126023 a(0)=0, a(1)=1; for n>1, a(n) = a(n-1)*(a(n-1)+a(n-2)).

0, 1, 1, 2, 6, 48, 2592, 6842880, 46842743439360, 2194242933464976548324966400, 4814702051061088283920560140388303599459408453566464000, 23181355840491850372772514246989811472332466216882815765831029699284672633019505150499832539732598430105600000

Offset: 0

Author

Franklin T. Adams-Watters, Feb 27 2007

Keywords

• easy
• nonn

Links

• Steven R. Finch, Substitution dynamics, January 23, 2014. [Cached copy, with permission of the author]
• Index entries for sequences of form a(n+1)=a(n)^2 + ...

Crossrefs

Cf. A064183.

Programs

Mathematica

a=0;b=1;lst={a,b};Do[c=(a+b)*b;AppendTo[lst,c];a=b;b=c,{n,2*3!}];lst (* Vladimir Joseph Stephan Orlovsky, Sep 05 2009 *)
RecurrenceTable[{a[0]==0, a[1]==1, a[n] == a[n-1]*(a[n-1]+a[n-2])}, a, {n, 0, 10}] (* Vaclav Kotesovec, Dec 18 2014 *)

PARI

a=0;b=1;vector(11,i,c=b*(b+a);a=b;b=c;a)

Formula

a(n) ~ c^(2^n), where c = 1.130839439573188327984771046199629891088102083459871373699856783789557668... . - Vaclav Kotesovec, Dec 18 2014