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Search: id:A003661
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| A003661 |
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Number of bipartite Steinhaus graphs on n nodes.
(Formerly M0996)
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+0
2
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| 1, 2, 4, 6, 9, 10, 13, 15, 19, 19, 21, 23, 27, 28, 31, 34, 39, 38, 39, 40, 43, 44, 47, 50, 55, 55, 57, 59, 63, 65, 69, 73, 79, 77, 77, 77, 79, 79, 81, 83, 87, 87, 89, 91, 95, 97, 101, 105, 111, 110, 111, 112, 115, 116, 119, 122, 127, 128, 131, 134, 139, 142, 147, 152, 159
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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W. M. Dymacek, M. Koerlin and T. Whaley, A survey of Steinhaus graphs, Proc. 8th Quadrennial International Conf. on Graph Theory, Combinatorics, Algorithms and Application, Kalamazoo, Mich. 1996, pages 313-323, Vol. I.
W. M. Dymacek and T. Whaley, Generating strings for bipartite Steinhaus graphs, Discrete Math. 141 (1995), pages 97-107.
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FORMULA
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a(n) <= (5n-7)/2 (n > 2) with equality for n=2^k + 1.
a(2k+1)=2a(k+1)+1; a(2k)=a(k)+a(k+1) for k >=2.
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MAPLE
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a := proc(n) if n=1 then 1 elif n=2 then 2 elif n=3 then 4 elif n mod 2 = 1 then 2*a((n+1)/2) + 1 else a(n/2)+a(n/2+1) fi end: seq(a(n), n=1..80);
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CROSSREFS
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Adjacent sequences: A003658 A003659 A003660 this_sequence A003662 A003663 A003664
Sequence in context: A047411 A138972 A050110 this_sequence A065387 A065388 A024978
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KEYWORD
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nonn
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AUTHOR
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njas, Mira Bernstein
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 26 2004
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