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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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3
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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; refs; listen; history; internal format)
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OFFSET
| 0,4
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COMMENTS
| 3^n=A091000(n)+3*a(n)+6*A091002(n)
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REFERENCES
| 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
| 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
| Sequence in context: A192778 A051138 A157101 * A078811 A093399 A123233
Adjacent sequences: A090998 A090999 A091000 * A091002 A091003 A091004
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Dec 12 2003
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