The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A306006 Number of non-isomorphic intersecting set-systems of weight n. 27
 1, 1, 1, 2, 3, 5, 10, 16, 30, 57 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS An intersecting set-system S is a finite set of finite nonempty sets (edges), any two of which have a nonempty intersection. The weight of S is the sum of cardinalities of its elements. Weight is generally not the same as number of vertices. LINKS EXAMPLE Non-isomorphic representatives of the a(6) = 10 set-systems: {{1,2,3,4,5,6}} {{5},{1,2,3,4,5}} {{1,5},{2,3,4,5}} {{3,4},{1,2,3,4}} {{1,2,5},{3,4,5}} {{1,3,4},{2,3,4}} {{3},{2,3},{1,2,3}} {{4},{1,4},{2,3,4}} {{1,2},{1,3},{2,3}} {{1,4},{2,4},{3,4}} CROSSREFS Cf. A007716, A034691, A048143, A049311, A116540, A283877, A293606, A293607, A304867, A305999, A305854-A305857, A306005-A306008. Sequence in context: A118728 A062860 A024369 * A047011 A259393 A018163 Adjacent sequences:  A306003 A306004 A306005 * A306007 A306008 A306009 KEYWORD nonn,more AUTHOR Gus Wiseman, Jun 16 2018 STATUS approved

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

Last modified February 20 19:57 EST 2020. Contains 332084 sequences. (Running on oeis4.)