A124042 Number of permutations of n distinct letters (ABCD...) each of which appears thrice with two fixed points.

0, 9, 378, 84510, 38358540, 31234760055, 41467520432646, 83805898840005132, 244832935610272588920, 993012060508835944545045, 5413243051841698780829328690, 38622438042365626607874252846474

Offset

0,2

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: A157567 A157593 A157602 * A297738 A225988 A012191

Adjacent sequences: A124039 A124040 A124041 * A124043 A124044 A124045

Keyword

nonn

Author

Zerinvary Lajos, Nov 02 2006

Status

approved