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A060018
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a(n) = floor(2*sqrt(n-2)).
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4
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0, 2, 2, 3, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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2,2
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LINKS
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FORMULA
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G.f.: (Sum_{k>=1} x^(k^2+2) + x^(k^2-k+3))/(1-x)
= (x^2 * (Theta3(x)-1) + x^(11/4) * Theta2(x))/(2-2*x) where Theta2 and Theta3 are Jacobi theta functions. - Robert Israel, Dec 09 2015
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MATHEMATICA
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PROG
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(PARI) { default(realprecision, 100); for (n=2, 1000, write("b060018.txt", n, " ", floor(2*sqrt(n - 2))); ) } \\ Harry J. Smith, Jul 01 2009
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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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STATUS
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approved
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