A055455 a(n) = A055450(n, n-5).

1, 6, 20, 48, 90, 132, 561, 2420, 10571, 46672, 207963, 934064, 4224685, 19225588, 87969426, 404479884, 1867924322, 8660317820, 40295911480, 188105782260, 880716750140, 4134823623820, 19461238795225, 91810738725036, 434062054130187, 2056265327125528

Offset: 5

Author

Clark Kimberling, May 18 2000

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 5..500

Crossrefs

Cf. A055450, A055451, A055452, A055453, A055454.

Programs

Magma

[1,6,20,48,90] cat [Floor(132*HypergeometricSeries2F1(10-n,13/2,8,-4)): n in [10..40]]; // G. C. Greubel, Jan 30 2024

Mathematica

Join[{1,6,20,48,90}, Table[132*Hypergeometric2F1[10-n,13/2,8,-4], {n, 10, 40}]] (* G. C. Greubel, Jan 30 2024 *)

SageMath

def A055455(n): return (1,6,20,48,90)[n-5] if n<10 else 132*hypergeometric([10-n,13/2],[8],-4).simplify()
[A055455(n) for n in range(5,41)] # G. C. Greubel, Jan 30 2024

Formula

a(n) = A055450(n, n-5), n >= 5.

a(n) = 132*Hypergeometric2F1([10-n, 13/2], [8], -4), for n >= 10. - G. C. Greubel, Jan 30 2024

Extensions

a(13) corrected and more terms from Sean A. Irvine, Mar 21 2022