OFFSET
0,4
COMMENTS
A derangement is a permutation without fixed points. Two permutations x,y commute if x*y = y*x.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..200
FORMULA
E.g.f.: (1 - x)^2 * exp(x) * B(x) where B(x) is the e.g.f. of A053529.
PROG
(PARI) seq(n)=Vec(serlaplace((1 - x)^2*exp(sum(k=1, n, (x^k/k)/(1-x^k) + O(x*x^n)) + x)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, May 05 2023
STATUS
approved