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, 17970749926243172352, 334353766096, 60108447043798927317622177792, 179774996243172352

Offset

1,1

Links

Table of n, a(n) for n=1..20.

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, 20); # 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

Status

approved