A292062 Wiener index of the n-transposition graph.
0, 1, 21, 552, 19560, 920160, 55974240, 4293596160, 406306575360, 46556342784000, 6357567896064000, 1020650937901056000, 190386526063878144000, 40844355820490686464000, 9987985777548364185600000, 2762125829379285162393600000, 857790151281459139077734400000
Offset: 1
Keywords
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
Programs
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Mathematica
Table[n! (n n! + (-1)^n StirlingS1[n + 1, 2])/2, {n, 20}] -
PARI
a(n) = n! * (n*n! - abs(stirling(n+1, 2, 1))) / 2; \\ Andrew Howroyd, Sep 08 2017
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
Extensions
Terms a(9) and beyond from Andrew Howroyd, Sep 08 2017