A124008 Number of permutations of n distinct letters (ABCD...) each of which appears thrice with n-4 fixed points.

9, 189, 1431, 5355, 14310, 31374, 60354, 105786, 172935, 267795, 397089, 568269

Offset

0,1

Links

Table of n, a(n) for n=0..11.

Example

1
0, 0, 0, 1
1, 0, "9", 0, 9, 0, 1
56, 216, 378, 435, 324, "189", 54", 27, 0, 1
13833, 49464, 84510, 90944, 69039, 38448, 16476, 5184, "1431", 216, 54, 0, 1
6699824, 23123880, 38358540, 40563765, 30573900, 17399178, 7723640, 2729295, 776520, 180100, 33372, "5355", 540, 90, 0, 1
etc...

Maple

p := (x, k)->k!^2*sum(x^j/((k-j)!^2*j!), j=0..k); R := (x, n, k)->p(x, k)^n; f := (t, n, k)->sum(coeff(R(x, n, k), x, j)*(t-1)^j*(n*k-j)!, j=0..n*k); for n from 0 to 6 do seq(coeff(f(t, n, 3), t, m)/3!^n, m=0..3*n); od;

Crossrefs

Cf. A059058, A027468, A059073, A000459.

Sequence in context: A351333 A196215 A196682 * A033713 A067422 A347855

Adjacent sequences: A124005 A124006 A124007 * A124009 A124010 A124011

Keyword

nonn

Author

Zerinvary Lajos, Nov 01 2006

Status

approved