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A292062 Wiener index of the n-transposition graph. 2
0, 1, 21, 552, 19560, 920160, 55974240, 4293596160, 406306575360, 46556342784000, 6357567896064000, 1020650937901056000, 190386526063878144000, 40844355820490686464000, 9987985777548364185600000, 2762125829379285162393600000, 857790151281459139077734400000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..50

Eric Weisstein's World of Mathematics, Transposition Graph

Eric Weisstein's World of Mathematics, Wiener Index

FORMULA

From Andrew Howroyd, Sep 08 2017: (Start)

a(n) = n! * A067318(n) / 2.

a(n) = n! * (n*n! - abs(Stirling1(n+1, 2))) / 2.

(End)

a(n) = (n!/2) * Sum_{k=1..n-1} abs(Stirling1(n, n-k))*k. - Andrew Howroyd, Dec 09 2017

MATHEMATICA

Table[n! (n n! + (-1)^n StirlingS1[n + 1, 2])/2, {n, 20}]

PROG

(PARI)

a(n) = n! * (n*n! - abs(stirling(n+1, 2, 1))) / 2; \\ Andrew Howroyd, Sep 08 2017

CROSSREFS

Cf. A067318, A296194.

Sequence in context: A015255 A034789 A297635 * A194022 A183730 A341572

Adjacent sequences:  A292059 A292060 A292061 * A292063 A292064 A292065

KEYWORD

nonn

AUTHOR

Eric W. Weisstein, Sep 08 2017

EXTENSIONS

Terms a(9) and beyond from Andrew Howroyd, Sep 08 2017

STATUS

approved

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Last modified October 18 17:19 EDT 2021. Contains 348068 sequences. (Running on oeis4.)