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A098267 Consider the family of directed graphs with loops. Sequence gives the triangle read by rows giving coefficients of polynomials arising from enumeration of those graphs on n arcs and loops. 0
1, 1, 1, 6, 6, 1, 12, 72, 62, 15, 1, 12, 492, 1322, 960, 260, 28, 1, 2520, 19320, 32550, 20202, 5600, 740, 45, 1, 10080, 230160, 827400, 1003632, 541576, 147862, 21600, 1690, 66, 1, 30240, 2372160, 17802120, 39440520, 37162384 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

REFERENCES

G. Paquin, Dénombrement de multigraphes enrichis, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004.

LINKS

Table of n, a(n) for n=0..40.

G. Paquin, Dénombrement de multigraphes enrichis, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004. [Cached copy, with permission]

EXAMPLE

1, x+x^2, 6x^2+6x^3+x^4, 12x^2+72x^3+62x^4+15x^5+x^6, 12x^2+492x^3+1322x^4+960x^5+260x^6+28x^7+x^8, 2520x^3+19320x^4+32550x^5+20202x^6+5600x^7+740x^8+45x^9+x^{10}, ...

CROSSREFS

Sequence in context: A194597 A105817 A093313 * A122193 A098369 A078740

Adjacent sequences:  A098264 A098265 A098266 * A098268 A098269 A098270

KEYWORD

nonn,tabf

AUTHOR

N. J. A. Sloane, Oct 26 2004

STATUS

approved

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Last modified July 24 11:17 EDT 2021. Contains 346273 sequences. (Running on oeis4.)