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A105076
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Numbers k such that 60*k^2 + 60*k + 1 is a square.
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0
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0, 1, 2, 11, 19, 90, 153, 712, 1208, 5609, 9514, 44163, 74907, 347698, 589745, 2737424, 4643056, 21551697, 36554706, 169676155, 287794595, 1335857546, 2265802057, 10517184216, 17838621864, 82801616185, 140443172858, 651895745267
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) = a(n-1) + 8*a(n-2) - 8*a(n-3) - a(n-4) + a(n-5).
G.f.: x^2*(1+x+x^2)/((1-x)*(x^4-8*x^2+1)). (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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