

A253207


a(n) = number of permutations of (1,2,...,n) producible by an ordered quadruple of distinct transpositions.


1



11, 59, 359, 1799, 7091, 22995, 64143, 159093, 359348, 752180, 1478204, 2754752, 4906202, 8402522, 13907394, 22337388, 34933761, 53348561, 79746821, 116926733, 168459797, 238853045, 333735545, 460071495, 626402322, 843120306, 1122776354
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OFFSET

4,1


LINKS

Colin Barker, Table of n, a(n) for n = 4..1000
Index entries for linear recurrences with constant coefficients, signature (9,36,84,126,126,84,36,9,1).


FORMULA

a(n) = n!*(1/(384*(n8)!)+1/(24*(n7)!)+13/(72*(n6)!)+1/(5*(n5)!)+1/(8*(n4)!)+1/(3*(n3)!)) for n>=8.


PROG

(PARI) Vec(x^4*(2*x^818*x^7+72*x^6168*x^5+254*x^4232*x^3+224*x^240*x+11)/(x1)^9 + O(x^100)) \\ Colin Barker, Dec 30 2014


CROSSREFS

Cf. A000914, for two transpositions, and A253171, for three.
Sequence in context: A249891 A186256 A164299 * A241860 A082884 A193230
Adjacent sequences: A253204 A253205 A253206 * A253208 A253209 A253210


KEYWORD

nonn,easy


AUTHOR

Andrew Woods, Dec 28 2014


STATUS

approved



