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Search: id:A091001
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| A091001 |
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Number of walks of length n between adjacent nodes on the Petersen graph. |
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+0
4
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| 0, 1, 0, 5, 4, 33, 56, 253, 588, 2105, 5632, 18261, 52052, 161617, 473928, 1443629, 4287196, 12948969, 38672144, 116365957, 348398820, 1046594561, 3136987480, 9416554845, 28238479724, 84737808793, 254168687136, 762595539893
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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3^n=A091000(n)+3*a(n)+6*A091002(n)
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REFERENCES
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N. Biggs, Algebraic Graph Theory, Cambridge, 2nd. Ed., 1993, p. 20.
F. Harary, Graph Theory, Addison-Wesley, 1969, p. 89.
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FORMULA
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G.f.: x(1-2x)/((1-x)(1+2x)(1-3x)); a(n)=3^n/10-4(-2)^n/15+1/6.
a(n)=(A000244(n)-A001045(n+1)(-1)^n+6*A001045(n)(-1)^(n+1))/10.
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CROSSREFS
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Sequence in context: A024067 A051138 A157101 this_sequence A078811 A093399 A123233
Adjacent sequences: A090998 A090999 A091000 this_sequence A091002 A091003 A091004
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Dec 12 2003
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