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A062259
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Number of (0,1)-strings of length n that avoid the substrings of substrings 11101011 and 101111.
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3
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1, 2, 4, 8, 16, 32, 63, 124, 243, 476, 933, 1830, 3590, 7043, 13818, 27110, 53186, 104342, 204701, 401588, 787846, 1545619, 3032243, 5948749, 11670441, 22895434, 44916973, 88119508, 172875575, 339152648, 665360153, 1305324126, 2560825244
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OFFSET
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0,2
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REFERENCES
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I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 2.8.4).
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LINKS
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FORMULA
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G.f.: (1+x+x^2+x^3+x^4+2*x^5+3*x^6+3*x^7+2*x^8+x^9)/(1-x-x^2-x^3-x^4-2*x^7-2*x^8-x^9-x^10). a(n) = a(n-1)+a(n-2)+a(n-3)+a(n-4)+2*a(n-7)+2*a(n-8)+a(n-9)+a(n-10).
Goulden and Jackson give the g.f. in the equivalent form (1+x^5+x^6-x^8-x^9-x^10)/(1-2*x+x^5-2*x^7+x^9+x^11). - N. J. A. Sloane, Apr 09 2011
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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