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Search: id:A160457
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| A160457 |
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Competition number of the complete bipartite graph K_n,n. |
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+0
2
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| 2, 1, 2, 5, 10, 17, 26, 37, 50, 65, 82, 101, 122, 145, 170, 197, 226, 257, 290, 325, 362, 401, 442, 485, 530, 577, 626, 677, 730, 785, 842, 901, 962, 1025, 1090, 1157, 1226, 1297, 1370, 1445, 1522, 1601, 1682, 1765, 1850, 1937, 20, 26, 2117, 2210, 2305, 2402
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Formula given on p. 3 of Sano.
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LINKS
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Yoshio Sano, The competition numbers of regular polyhedra, May 12, 2009.
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FORMULA
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a(n) = n^2 - 2*n + 2, for nonnegative n.
a(n)=2*n+a(n-1)-5 (with a(1)=2) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 08 2009]
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EXAMPLE
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a(11) = 11^2 - 2*11 + 2 = 101.
For n=2, a(2)=2*2+2-5=1; n=3, a(3)=2*3+1-5=2; n=4, a(4)=2*4+2-5=5 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 08 2009]
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CROSSREFS
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Cf. A160450.
Sequence in context: A129394 A049901 A117715 this_sequence A107087 A115141 A031148
Adjacent sequences: A160454 A160455 A160456 this_sequence A160458 A160459 A160460
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), May 14 2009
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EXTENSIONS
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More terms a(27)-a(52) from Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 08 2009
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