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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
OFFSET
1,3
LINKS
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
Sequence in context: A015255 A034789 A297635 * A194022 A183730 A341572
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Sep 08 2017
EXTENSIONS
Terms a(9) and beyond from Andrew Howroyd, Sep 08 2017
STATUS
approved