[seqfan] An alternating sequence whose sequence of absolute values appears in the OEIS

[Jack Grahl]

Dear all,

The sequence g(n) = (-1)^n(3^n -1)/2 is described in the 1973 article 'Some
polynomials associated with graphs' by Tutte. He defines a graph polynomial
g(G) and thence a(n) := g(Xn) where Xn is the multigraph with 1 vertex and
n loops.

This is a fact which I don't think it's covered by any of the numerous
definitions and remarks on https://oeis.org/A007051 [a(n) = (3^n-1)/2,
without the alternating signs]. Does it make more sense to add the
alternating version of the sequence with the formula and this definition?
Or should I just as a remark to A007051 that this related sequence is
mentioned in the paper and give the reference?

Thanks for advice. Let me know if anyone wants any more information.

Yours,
Jack Grahl