A011268 Triangle read by rows: number of P-graphs by number of edges and number of non-root nodes.

1, 1, 2, 1, 10, 3, 1, 30, 44, 4, 1, 70, 284, 134, 5, 1, 140, 1224, 1594, 329, 6, 1, 252, 4110, 11330, 6552, 700, 7, 1, 420, 11616, 58432, 71484, 21822, 1344, 8, 1, 660, 28908, 241098, 534562, 347274, 62370, 2388, 9, 1, 990, 65208, 842842, 3069360, 3612924

Offset

2,3

Links

Table of n, a(n) for n=2..52.

R. C. Read, On the enumeration of a class of plane multigraphs, Aequat. Math., 31 (1986), 47-63.

Formula

Reference gives generating function.

Crossrefs

Sequence in context: A144274 A144275 A247236 * A332080 A225911 A163235

Adjacent sequences: A011265 A011266 A011267 * A011269 A011270 A011271

Keyword

tabl,nonn,easy,nice

Author

N. J. A. Sloane

Extensions

More terms from Pab Ter (pabrlos(AT)yahoo.com), May 27 2004

Status

approved