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A290591
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Number of irredundant sets in the n-web graph.
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1
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4, 22, 112, 618, 3044, 14026, 70340, 347074, 1713820, 8430362, 41516292, 204628626, 1008216460, 4967464650, 24473678612, 120581823170, 594106884060, 2927147525626, 14421969381220, 71056635221618, 350094259434668, 1724905262555178, 8498562511858612
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OFFSET
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1,1
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COMMENTS
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The n-web graph is well defined for n >= 3. Sequence extended to n=1 via the number of period n periodic solutions on a larger graph. - Andrew Howroyd, Aug 07 2017
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LINKS
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Eric Weisstein's World of Mathematics, Web Graph
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FORMULA
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Empirical: a(n) = 4*a(n-1) + 3*a(n-2) + 4*a(n-3) + 22*a(n-4) + 12*a(n-5) - 164*a(n-6) + 80*a(n-7) - 24*a(n-8) + 80*a(n-9) for n > 9.
Empirical g.f.: 2*x*(2 + 3*x + 6*x^2 + 44*x^3 + 30*x^4 - 492*x^5 + 280*x^6 - 96*x^7 + 360*x^8)/(1 - 4*x - 3*x^2 - 4*x^3 - 22*x^4 - 12*x^5 + 164*x^6 - 80*x^7 + 24*x^8 - 80*x^9).
(End)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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