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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 (list; graph; refs; listen; history; text; internal format)
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*(n-8)!)+1/(24*(n-7)!)+13/(72*(n-6)!)+1/(5*(n-5)!)+1/(8*(n-4)!)+1/(3*(n-3)!)) for n>=8.

PROG

(PARI) Vec(-x^4*(2*x^8-18*x^7+72*x^6-168*x^5+254*x^4-232*x^3+224*x^2-40*x+11)/(x-1)^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

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Last modified July 5 00:40 EDT 2020. Contains 335457 sequences. (Running on oeis4.)