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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| a(28) > 2*10^6. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), May 30 2010]
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EXAMPLE
| n = 14: a(14) = 35950, Pi(35950^2) = Pi(1292402500) = 64866916 = 8054^2
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MATHEMATICA
| 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 (rgwv(at)rgwv.com), Feb 03 2006
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PROG
| (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
| Cf. A000720, A115835: Square root of pi(A064523(n)).
Sequence in context: A000214 A060955 A024329 * A139430 A143386 A151885
Adjacent sequences: A064520 A064521 A064522 * A064524 A064525 A064526
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KEYWORD
| nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Oct 07 2001
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and Labos E. (labos(AT)ana.sote.hu), Oct 08 2001
Further terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 16 2001
a(20) from Robert G. Wilson v (rgwv(at)rgwv.com), Feb 03 2006
Added missing terms 134141, 142413, 194711 and a(24)-a(27) from Donovan Johnson (donovan.johnson(AT)yahoo.com), May 30 2010
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