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A029700 Number of words of length 6 in the n(n-1)/2 transpositions of S[ n ] equivalent to the identity. 1
0, 1, 243, 3936, 20860, 72315, 197421, 460768, 961416, 1843245, 3306655, 5621616, 9142068, 14321671, 21730905, 32075520, 46216336, 65190393, 90233451, 122803840, 164607660, 217625331, 284139493, 366764256, 468475800, 592644325, 743067351, 924004368 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).

FORMULA

a(n) = n*(n-1)*(15*n^4 + 30*n^3 - 105*n^2 - 700*n + 1344)/8.

G.f.: -x^2*(481*x^4 - 1624*x^3 + 2256*x^2 + 236*x + 1) / (x-1)^7. - Colin Barker, May 28 2015

PROG

(MAGMA) [n*(n-1)*(15*n^4+30*n^3-105*n^2-700*n+1344)/8: n in [1..45]]; // Vincenzo Librandi, Jun 30 2011

(PARI) concat(0, Vec(-x^2*(481*x^4-1624*x^3+2256*x^2+236*x+1) / (x-1)^7 + O(x^100))) \\ Colin Barker, May 28 2015

CROSSREFS

Sequence in context: A226777 A016757 A133550 * A224003 A232027 A183808

Adjacent sequences:  A029697 A029698 A029699 * A029701 A029702 A029703

KEYWORD

nonn,easy

AUTHOR

Paolo Dominici (pl.dm(AT)libero.it)

EXTENSIONS

a(1) corrected by Vincenzo Librandi, Jun 30 2011

STATUS

approved

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Last modified November 21 16:04 EST 2019. Contains 329371 sequences. (Running on oeis4.)