A115033 Alternately multiply and divide, with a(1)=2 and a(2)=3.

2, 3, 6, 2, 12, 6, 72, 12, 864, 72, 62208, 864, 53747712, 62208, 3343537668096, 53747712, 179707499645975396352, 3343537668096, 600858794305667322270155425185792, 179707499645975396352, 107978831564966913814384922944738457859243070439030784, 600858794305667322270155425185792

Offset: 1

Author

Giovanni Teofilatto, Feb 26 2006

Keywords

• easy
• nonn

Crossrefs

Cf. A115034, A174348.

Programs

Maple

addmul:=proc(k,m,maxn) local f:
  f:= proc(n) if n::even
    then k^combinat:-fibonacci(n/2-1)  *m^combinat:-fibonacci(n/2-2)
    else k^combinat:-fibonacci((n+1)/2)*m^combinat:-fibonacci((n-1)/2)
    fi
  end proc:
  map(f, [$1..maxn]);
end proc: # after Robert Israel in A174348
addmul(2,3,22)[]; # Georg Fischer, Jun 18 2021

Mathematica

nxt[{a_, b_}]:={a*b, (a*b)/b}; NestList[nxt, {2,3}, 10]//Flatten (* Georg Fischer, Jun 18 2021 *)

Formula

a(2*k) = a(2*k-3); a(2*k+1) = a(2*k)*a(2*k-1). - Georg Fischer, Jun 18 2021

Extensions

Definition adapted to offset by Georg Fischer, Jun 18 2021

Corrected and extended by Michel Marcus, May 31 2025