A215460 a(n) = floor(n!^2 / n^n).

1, 1, 1, 2, 4, 11, 30, 96, 339, 1316, 5584, 25733, 128025, 683949, 3905083, 23731187, 152934464, 1041782238, 7479469995, 56448098958, 446768591341, 3700276748921, 32007269639380, 288630046441757, 2708888570942365, 26419890078249485, 267389254029561667, 2804508541393392135, 30446382653772707171, 341729529206733994569

Offset

1,4

Links

Paolo Xausa, Table of n, a(n) for n = 1..500

Example

a(4) = floor((4!)^2 / (4^4)) = floor(24^2 / 256) = floor(2.25) = 2.

Mathematica

A215460[n_] := Quotient[n!^2, n^n];
Array[A215460, 30] (* Paolo Xausa, Aug 05 2025 *)

Prog

(Python)
f = 1
for n in range(1, 33):
    print(f*f // n**n)
    f *= n+1

Crossrefs

Cf. A064546, A063709, A055775.

Sequence in context: A148157 A141268 A135527 * A339225 A148158 A148159

Adjacent sequences: A215457 A215458 A215459 * A215461 A215462 A215463

Keyword

nonn

Author

Alex Ratushnyak, Aug 11 2012

Extensions

More terms from Paolo Xausa, Aug 05 2025

Status

approved