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3, 6, 17, 66, 327, 1958, 13701, 109602, 986411, 9864102, 108505113, 1302061346, 16926797487, 236975164806, 3554627472077, 56874039553218, 966858672404691, 17403456103284422, 330665665962404001, 6613313319248080002
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) is an upper bound on the Ramsey numbers in A003323. - D. G. Rogers (drogers(AT)turing.une.edu.au), Aug 27 2006
There is a nice derivation of the recurrence relation given in the Walker reference.
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REFERENCES
| R. C. Walker, A graph coloring theorem, Math. Gaz., 60 (1976), 54-57.
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MATHEMATICA
| f[n_] := n*(f[n - 1] - 1) + 2; f[0]=2; ff[n_]:=(1/(1+n))(1+E*Gamma[1+n, 1]-E*(n^2)*Gamma[1+n, 1]+E*n*Gamma[2+n, 1]) (Spindler)
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CROSSREFS
| Cf. A003323.
Cf. A001339.
Sequence in context: A117712 A106158 A003323 * A195995 A078318 A193433
Adjacent sequences: A073588 A073589 A073590 * A073592 A073593 A073594
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 28 2002
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