A344919 a(n) = n^n - n*(n + 1) / 2.

1, 0, 1, 21, 246, 3110, 46635, 823515, 16777180, 387420444, 9999999945, 285311670545, 8916100448178, 302875106592162, 11112006825557911, 437893890380859255, 18446744073709551480, 827240261886336764024, 39346408075296537575253, 1978419655660313589123789, 104857599999999999999999790

Offset: 0

Author

Peter Luschny, Jun 19 2021

Keywords

• nonn
• easy

Crossrefs

Cf. A000217, A000312, A036679, A058126.

Programs

Mathematica

Join[{1},Table[n^n-(n(n+1))/2,{n,20}]] (* Harvey P. Dale, Sep 07 2024 *)

Python

def A344919(n):
    return (n**n)-(n*(n+1)//2) # Karl-Heinz Hofmann, Jun 19 2021

Formula

a(n) = Product_{j=1..n} n - Sum_{j=1..n} j.

a(n) = A000312(n) - A000217(n).