A057157 Number of non-invertible functions from {0,1}^n to {0,1}^n.

0, 2, 232, 16736896, 18446723150919663616, 1461501637330639787366751139186115801643772542976

Offset: 0

Author

Henry Bottomley, Aug 15 2000

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..10

Crossrefs

Cf. A057156, A000722, A036679, A000079.

Programs

Magma

[(2^n)^(2^n)-Factorial(2^n): n in [0..5]]; // Vincenzo Librandi, Aug 22 2011

Mathematica

Table[(2^n)^(2^n) - (2^n)!, {n,0,5}] (* G. C. Greubel, Nov 08 2018 *)

PARI

vector(6,n,n--; (2^n)^(2^n) - (2^n)!) \\ G. C. Greubel, Nov 08 2018

Formula

a(n) = (2^n)^(2^n) - (2^n)! = A057156(n) - A000722(n) = A036679(A000079(n)).