A062779 a(n) = 2*n*(2*n)!.

0, 4, 96, 4320, 322560, 36288000, 5748019200, 1220496076800, 334764638208000, 115242726703104000, 48658040163532800000, 24728016011107368960000, 14890761641597746544640000, 10485577989291746525184000000

Offset: 0

Author

Jason Earls, Jul 18 2001

Keywords

• easy
• nonn

References

• Jerome Spanier and Keith B. Oldham, "Atlas of Functions", Hemisphere Publishing Corp., 1987, chapter 38, equation 38:6:2 at page 364.

Links

• Wikipedia, Cosine integral.
• Wikipedia, Hyperbolic cosine integral.

Crossrefs

Cf. A001563, A001620, A010050, A099282, A099284.

Programs

Mathematica

a[n_] := 2*n*(2*n)!; Array[a, 14, 0] (* Amiram Eldar, Feb 14 2021 *)

PARI

for(n=0,22,print((2*n)*(2*n)!))

Formula

From Amiram Eldar, Feb 14 2021: (Start)

a(n) = A001563(2*n) = 2*n*A010050(n).

Sum_{n>=1} 1/a(n) = Chi(1) - gamma = A099284 - A001620, where Chi(x) is the hyperbolic cosine integral

Sum_{n>=1} (-1)^(n+1)/a(n) = gamma - Ci(1) = A001620 - A099282, where Ci(x) is the cosine integral. (End)