A341302 a(n) = n! + (n-1)! + n-2.

1, 3, 9, 32, 147, 844, 5765, 45366, 403207, 3991688, 43545609, 518918410, 6706022411, 93405312012, 1394852659213, 22230464256014, 376610217984015, 6758061133824016, 128047474114560017, 2554547108585472018, 53523844179886080019, 1175091669949317120020

Offset: 1

Author

N. J. A. Sloane, Feb 13 2021

Keywords

• nonn

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..449
• Michael Engen and Vincent Vatter, Containing all permutations, Amer. Math. Monthly, 128 (2021), 4-24; arXiv preprint, arXiv:1810.08252 [math.CO], 2018-2020.

Programs

Mathematica

Array[#2 + (#1 + 1) #2 + #1 - 1 & @@ {#, #!} &, 22, 0] (* Michael De Vlieger, Apr 07 2021 *)

Formula

E.g.f.: (1/(1 - x) - exp(x)) * (2 - x) - log(1 - x). - Ilya Gutkovskiy, Feb 15 2021