A109213 Product of a(n-2) and digit reversal of a(n-1).
1, 2, 2, 4, 8, 32, 184, 15392, 5400584, 74651892640, 25003708306137848, 6335942056759761366725617280, 20682199297864337408779128828731176793076928
Offset: 1
Examples
a(5)=8, a(6)=32, R(32)=23, hence a(7)=8*23=184; R(184)=841, a(8)=32*841=15392, etc.
Programs
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Mathematica
a[1]=1;a[2]=2;a[n_]:=a[n]=a[n-2]*FromDigits[Reverse[IntegerDigits[a[n-1]]]]; A109213=Table[a[n], {n, 13}] nxt[{a_,b_}]:={b,a*IntegerReverse[b]}; NestList[nxt,{1,2},15][[All,1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 09 2017 *)
Formula
a(n)=a(n-2)*R(a(n-1)).
Comments