A322095 Number of permutations of 7 copies of 1..n with no element equal to another within a distance of 1.
1, 0, 2, 339720, 549023310936, 4383995385521886720, 131828993822765959468851600, 12202002913678756821228939869239920, 2988325485815656468293009880545684170044800, 1723427149081248135793318785599849462668815779427840
Offset: 0
Keywords
Links
- Seiichi Manyama, Table of n, a(n) for n = 0..80
Formula
a(n) = n! * A190836(n).
a(n) = Integral_{0..infinity} (Sum_{k=1..7} (-1)^(7-k) * binomial(6, 7-k) * x^k/k!)^n * exp(-x) dx.