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.

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

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 * A366138 A122193 A348622

Adjacent sequences: A098264 A098265 A098266 * A098268 A098269 A098270

Keyword

nonn,tabf

Author

N. J. A. Sloane, Oct 26 2004

Status

approved