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A098821
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a(n) = (n-2) * 2^(n-1) + 5.
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0
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4, 4, 5, 9, 21, 53, 133, 325, 773, 1797, 4101, 9221, 20485, 45061, 98309, 212997, 458757, 983045, 2097157, 4456453, 9437189, 19922949, 41943045, 88080389, 184549381, 385875973, 805306373, 1677721605, 3489660933, 7247757317
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,1
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REFERENCES
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G. H. Hardy and J. E. Littlewood, "Some problems of partitio numerorum (VI): Further researches in Waring's Problem", Math. Z. vol. 23, 1-37, (1925)
T. D. Wooley, "Large improvements in Waring's Problem", Ann. Math. vol. 135, 131-164 (1992)
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LINKS
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FORMULA
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G.f.: (4-16*x+17*x^2)/(1-5*x+8*x^2-4*x^3).
a(n)=5*a(n-1)-8*a(n-2)+4*a(n-3). (End)
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EXAMPLE
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a(5) = 3*2^4 + 5 = 53.
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MATHEMATICA
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LinearRecurrence[{5, -8, 4}, {4, 4, 5}, 40] (* Harvey P. Dale, Feb 22 2013 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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