A267575 Number of size 3 subsets of S_n that generate a transitive group.

20, 1932, 269040, 60018480, 20842305120, 10739272592160, 7859814146553600, 7880871595516819200, 10509569407728543398400, 18186461035281996953126400, 39999355842324635340366182400, 109852416743246886658078908979200, 371006429409575280027759776435712000

Offset

3,1

Links

Table of n, a(n) for n=3..15.

Formula

a(n) = (A220754(n) - 6*A266910 - (n-1)!)/6.

Mathematica

nn = 15; b = Sum[n!^3 x^n/n!, {n, 0, nn}]; a = Sum[n!^2 x^n/n!, {n, 0,
   nn}]; c = (Range[0, nn]! CoefficientList[Series[Log[a], {x, 0, nn}], x] - Table[(n - 1)!, {n, 0, nn}])/ 2; Drop[((Range[0, nn]!CoefficientList[Series[Log[b], {x, 0, nn}], x]) - 6 c - Table[(n - 1)!, {n, 0, nn}])/6, 3]

Crossrefs

Sequence in context: A172556 A246619 A222973 * A072818 A123479 A071152

Adjacent sequences: A267572 A267573 A267574 * A267576 A267577 A267578

Keyword

nonn

Author

Geoffrey Critzer, Jan 17 2016

Status

approved