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

1,1

Links

Table of n, a(n) for n=1..22.

Formula

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

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 *)

Crossrefs

Cf. A115034, A174348.

Sequence in context: A275666 A330666 A319432 * A214630 A093396 A189971

Adjacent sequences: A115030 A115031 A115032 * A115034 A115035 A115036

Keyword

easy,nonn

Author

Giovanni Teofilatto, Feb 26 2006

Extensions

Definition adapted to offset by Georg Fischer, Jun 18 2021

Corrected and extended by Michel Marcus, May 31 2025

Status

approved