A374662 a(n) = (1/2)*Product_{k=0..n} (F(k)+2), where F=A000045 (Fibonacci numbers).

1, 3, 9, 36, 180, 1260, 12600, 189000, 4347000, 156492000, 8920044000, 811724004000, 118511704584000, 27850250577240000, 10555244968773960000, 6459809920889663520000, 6388752011759877221280000, 10215614466804043676826720000, 26417579011155256948273897920000

Offset: 0

Author

Clark Kimberling, Aug 03 2024

Keywords

• nonn

Comments

a(n+1)/a(n) is an integer for n>=0, so (a(n)) is a divisibility sequence.

Crossrefs

Cf. A000045, A082480.

Programs

Mathematica

q[n_] := Fibonacci[n]
p[n_] := Product[q[k] + 2, {k, 0, n}]
Table[Simplify[p[n]/2], {n, 0, 20}]

PARI

a(n) = prod(k=0, n, fibonacci(k)+2)/2; \\ Michel Marcus, Aug 04 2024