The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A123547 Triangle read by rows: T(n,k) = number of unlabeled bicolored graphs with no isolated nodes having 2n nodes and k edges, with n nodes of each color. Here n >= 0, 0 <= k <= n^2. 3
 1, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 1, 2, 4, 3, 2, 1, 1, 0, 0, 0, 0, 1, 2, 8, 14, 21, 20, 20, 12, 9, 4, 2, 1, 1, 0, 0, 0, 0, 0, 1, 2, 10, 31, 76, 137, 221, 285, 321, 301, 253, 182, 122, 69, 38, 19, 10, 4, 2, 1, 1, 0, 0, 0, 0, 0, 0, 1, 2, 11, 43, 162, 451, 1121, 2314, 4255, 6702 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,13 COMMENTS The colors may be interchanged. REFERENCES R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1978. LINKS R. W. Robinson, Rows 0 through 7, flattened F. Harary, L. March and R. W. Robinson, On enumerating certain design problems in terms of bicolored graphs with no isolates, Environment and Planning, B 5 (1978), 31-43. F. Harary, L. March and R. W. Robinson, On enumerating certain design problems in terms of bicolored graphs with no isolates, Environment and Planning B: Urban Analytics and City Science, 5 (1978), 31-43. [Annotated scanned copy] CROSSREFS Row sums give A007140. Cf. A007139, A106498 (gives beginning of this triangle). Sequence in context: A109158 A307500 A049245 * A123551 A286275 A029717 Adjacent sequences: A123544 A123545 A123546 * A123548 A123549 A123550 KEYWORD nonn,tabf AUTHOR N. J. A. Sloane, Nov 14 2006 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 6 20:42 EDT 2024. Contains 374983 sequences. (Running on oeis4.)