A023557 Convolution of A023531 and Fibonacci numbers.

0, 1, 1, 2, 4, 6, 10, 16, 27, 43, 70, 113, 183, 297, 480, 777, 1257, 2034, 3291, 5326, 8617, 13943, 22560, 36503, 59063, 95566, 154630, 250196, 404826, 655022, 1059848, 1714870, 2774718, 4489588, 7264307, 11753895, 19018202, 30772097, 49790299, 80562396, 130352695, 210915091, 341267786

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Crossrefs

Cf. A000045, A023531.

Programs

PARI

a(n) = sum(k=1, n, issquare(8*k+9)*fibonacci(n-k+1)); \\ Michel Marcus, Jan 26 2023

Formula

a(n) = a(n-1)+a(n-2)+1 if n mod 4 = 0, else a(n) = a(n-1)+a(n-2), with offset 0. [Gary Detlefs, Dec 05 2010]

Extensions

More terms from Michel Marcus, Jan 26 2023