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A322126
Number of permutations of the multiset {1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,...,n,n,n,n,n} with no two consecutive terms equal.
2
1, 0, 2, 7188, 134631576, 7946203275000, 1210527140790855600, 411490045733601418421040, 280031356887267221923677137280, 351026687723982522494728236869341440, 758933713536173718404757245269681913222400
OFFSET
0,3
LINKS
FORMULA
a(n) = n! * A190833(n).
a(n) = Integral_{0..infinity} (x - 2 * x^2 + x^3 - 1/6 * x^4 + 1/120 * x^5)^n * exp(-x) dx.
MATHEMATICA
a[n_] := Integrate[(x - 2 * x^2 + x^3 - 1/6 * x^4 + 1/120 * x^5)^n * Exp[-x], {x, 0, Infinity}]; Array[a, 10, 0] (* Stefano Spezia, Nov 27 2018 *)
CROSSREFS
Row 5 of A322093.
Sequence in context: A129058 A129057 A201508 * A272241 A171939 A104904
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 27 2018
STATUS
approved