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A339286
Total number of interior vertices in the multigraphs of all unoriented series-parallel networks with n edges.
1
0, 1, 4, 17, 62, 255, 1026, 4363, 18656, 81446, 357708, 1584110, 7042396, 31429998, 140626375, 630640342, 2833200433, 12748771157, 57445747751, 259170739397, 1170566884224, 5292311737901, 23949417255984, 108470668735077, 491664303153769, 2230174016940385, 10122784007130716
OFFSET
1,3
COMMENTS
See A339285 for additional details.
FORMULA
a(n) = Sum_{k=1..n-1} k*A339285(n,k).
PROG
(PARI) \\ See A339285 for VertexWeighted.
seq(n)={subst(deriv(VertexWeighted(n, x, y)), y, 1)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Nov 30 2020
STATUS
approved