A088979 a(n) = n! - ((n-1)!!)^2.

1, 2, 15, 56, 495, 2736, 29295, 215424, 2735775, 25171200, 370945575, 4103654400, 68916822975, 891494553600, 16813959537375, 249145395609600, 5214921734397375, 87125481883238400, 2004231846526284375, 37283094761472000000, 934957186489800849375

Offset

2,2

Links

Table of n, a(n) for n=2..22.

Formula

E.g.f.: 1/(1 - x) - (1 + arcsin(x))/sqrt(1 - x^2). - Benedict W. J. Irwin, Oct 14 2016

Mathematica

Table[CoefficientList[Series[1/(1-x)-(1+ArcSin[x])/Sqrt[1-x^2], {x, 0, 20}], x][[n]](n-1)!, {n, 3, 20}] (* Benedict W. J. Irwin, Oct 14 2016 *)

Crossrefs

Cf. A006882.

Bisection gives A151816.

Sequence in context: A142861 A305673 A268761 * A265909 A034571 A295828

Adjacent sequences: A088976 A088977 A088978 * A088980 A088981 A088982

Keyword

nonn,changed

Author

Vladeta Jovovic, Oct 31 2003

Extensions

More terms from Ray Chandler, Nov 06 2003

Status

approved