A076776 a(0) = 1, a(1) = 2, a(2) = 5; for n > 2, a(n) = a(n-1)*a(n-2).

1, 2, 5, 10, 50, 500, 25000, 12500000, 312500000000, 3906250000000000000, 1220703125000000000000000000000, 4768371582031250000000000000000000000000000000000

Offset: 0

Author

Emily Shields (emilyshields_2001(AT)hotmail.com), Nov 14 2002

Keywords

• nonn

Crossrefs

Cf. A000045, A000301, A010098, A010099.

Programs

Maple

with(combinat, fibonacci):A076776 := n->2^fibonacci(n-2)*5^fibonacci(n-1);

Mathematica

nxt[{a_,b_}]:={b,a*b}; Join[{1},NestList[nxt,{2,5},15][[All,1]]] (* Harvey P. Dale, Jun 07 2021 *)

Formula

a(n) = 2^fibonacci(n-2)*5^fibonacci(n-1)for n>=2, fibonacci(n)=A000045(n). - Vladeta Jovovic and Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Nov 16 2002

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Nov 16 2002