A061121 Number of degree-n permutations of order exactly 6.

0, 0, 0, 0, 20, 240, 1470, 10640, 83160, 584640, 4496030, 42658440, 371762820, 3594871280, 38650622010, 396457108320, 4330689250160, 53963701424640, 641211774798510, 8205894865096280, 113786291585124060

Offset

1,5

Links

Table of n, a(n) for n=1..21.

Formula

E.g.f.: exp(x)-exp(x+1/2*x^2)-exp(x+1/3*x^3)+exp(x+1/2*x^2+1/3*x^3+1/6*x^6).

Mathematica

nn=21; Range[0, nn]!CoefficientList[Series[(Exp[x^6/6]-1)Exp[x+x^2/2+x^3/3]+(Exp[x^2/2]-1)(Exp[x^3/3]-1)Exp[x], {x, 0, nn}], x]//Rest  (* Geoffrey Critzer, Feb 04 2013 *)

Crossrefs

Cf. A000085, A001470, A001472, A052501, A053496-A053505, A001189, A001471, A001473, A061121-A061128.

Sequence in context: A163004 A278320 A061139 * A073398 A040075 A138442

Adjacent sequences: A061118 A061119 A061120 * A061122 A061123 A061124

Keyword

easy,nonn

Author

Vladeta Jovovic, Apr 14 2001

Status

approved