A162992 The second right hand column of triangle A162990.

36, 144, 1600, 32400, 1016064, 45158400, 2687385600, 205752960000, 19670999040000, 2294425328025600, 320461058211840000, 52778155948277760000, 10118415696592896000000, 2233485391313240064000000, 562282428913542978600960000, 160118707296083137265664000000

Offset

2,1

Links

Table of n, a(n) for n=2..17.

Formula

a(n) = ((n+1)!/(n-1))^2.

a(n) = A052747(n+1)^2.

From Amiram Eldar, Feb 27 2026: (Start)

Sum_{n>=2} 1/a(n) = BesselI(0, 2) + 4 * BesselI(2, 2) - 5 = A070910 + 4 * A229020 - 5.

Sum_{n>=2} (-1)^n/a(n) = 3 - 3 * BesselJ(0, 2) - 4 * BesselJ(1, 2) = 3 - 3 * A091681 - 4 * A348607. (End)

Mathematica

Array[((#+1)!/(#-1))^2 &, 20, 2] (* Paolo Xausa, Apr 01 2024 *)

Crossrefs

A052747(n+1) equals the square root of a(n).

A162991 is the first right hand column of triangle A162990.

Cf. A070910, A091681, A229020, A348607.

Sequence in context: A110754 A299854 A154711 * A037072 A370453 A076432

Adjacent sequences: A162989 A162990 A162991 * A162993 A162994 A162995

Keyword

easy,nonn

Author

Johannes W. Meijer, Jul 21 2009

Status

approved