A162991 The first right hand column of triangle A162990.

4, 9, 64, 900, 20736, 705600, 33177600, 2057529600, 162570240000, 15933509222400, 1896219279360000, 269276305858560000, 44970736429301760000, 8724552309817344000000, 1945613940877311344640000, 494193541037293633536000000, 141835256289955997024256000000

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Formula

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

a(n) = A001048(n)^2.

From Amiram Eldar, Feb 27 2026: (Start)

Sum_{n>=1} 1/a(n) = 2 * BesselI(2, 2) - 1 = A393776.

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

Mathematica

Array[((#+1)!/#)^2 &, 20] (* Paolo Xausa, Mar 31 2024 *)

Crossrefs

A001048(n) equals the square root of a(n).

A162992 is the second right hand column of triangle A162990.

Cf. A348607, A393776.

Sequence in context: A092396 A184877 A055859 * A062926 A069020 A220189

Adjacent sequences: A162988 A162989 A162990 * A162992 A162993 A162994

Keyword

easy,nonn

Author

Johannes W. Meijer, Jul 21 2009

Status

approved