A179870 a(n) = ((n-1)! * (n+1)!) ^ 2.

4, 36, 2304, 518400, 298598400, 365783040000, 842764124160000, 3344930808791040000, 21407557176262656000000, 209815467884550291456000000, 3021342737537524196966400000000, 61783437639904832303765913600000000

Offset: 1

Author

Jaroslav Krizek, Jul 30 2010

Keywords

• nonn
• easy

Programs

Mathematica

Table[((n-1)!(n+1)!)^2,{n,15}] (* Harvey P. Dale, Jul 12 2020 *)

PARI

a(n)=(n-1)!^4*(n^4+2*n^3+n^2) \\ Charles R Greathouse IV, Jan 03 2013

Formula

a(n) = A175430(n) ^ 2 = ((Product_(k=1,2,...,n) k*A020725(k)) / n) ^ 2 = ((Product_(k=1,2,...,n) k*(k+1)) / n) ^ 2.