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A064523
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Numbers n such that pi(n^2) is a square.
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2
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1, 3, 5, 10, 2640, 8304, 11699, 15330, 16810, 16910, 22463, 25906, 26652, 35950, 72429, 75470, 134141, 142413, 194711, 270353, 296073, 371964, 496254, 654609, 1640679, 1729409, 1854680, 4434965, 4973898, 5584120, 5783816
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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n = 14: a(14) = 35950, Pi(35950^2) = Pi(1292402500) = 64866916 = 8054^2
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MATHEMATICA
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Do[ If[ IntegerQ[ Sqrt[ PrimePi[n^2]]], Print[n]], {n, 1, 400000} ]
lst = {}; Do[ If[ IntegerQ@ Sqrt@ PrimePi[n^2], AppendTo[lst, n]; Print@n], {n, 520000}]; lst (* Robert G. Wilson v, Feb 03 2006 *)
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PROG
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(PARI) pi(x, c=0) = forprime(p=2, x, c++); c for(n=1, 10^6, if(issquare(pi(n^2)), print1(n, " ")))
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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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Added missing terms 134141, 142413, 194711 and a(24)-a(27) from Donovan Johnson, May 30 2010
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STATUS
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approved
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