A335088 a(n) = n! * [x^n] exp(Sum_{k=1..n, gcd(n,k) = 1} x^k / k).
1, 1, 1, 4, 9, 96, 145, 4320, 11025, 179200, 693441, 36288000, 62610625, 5748019200, 15259154625, 378002200576, 4108830350625, 334764638208000, 643373556450625, 115242726703104000, 309281197713168681, 14870534508544000000, 168541849294187630625
Offset: 0
Keywords
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..450
Programs
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Maple
b:= proc(n, m) option remember; `if`(n=0, 1, add(`if`( igcd(j, m)=1, b(n-j, m), 0)*(n-1)!/(n-j)!, j=1..n)) end: a:= n-> b(n$2): seq(a(n), n=0..23); # Alois P. Heinz, Oct 12 2020 -
Mathematica
Table[n! SeriesCoefficient[Exp[Sum[Boole[GCD[n, k] == 1] x^k/k, {k, 1, n}]], {x, 0, n}], {n, 0, 22}]
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