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A274120
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Squares that are the sum of the first n odd primes for some n.
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1
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OFFSET
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1,1
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COMMENTS
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a(9), if it exists, is larger than 2*10^26 and would require adding more than 3.6*10^12 primes. - Giovanni Resta, Jun 12 2016
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LINKS
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EXAMPLE
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961 is in the sequence because 961 = 31^2. Also, 3+5+7+...+83+89 = 961.
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MATHEMATICA
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Select[s=0; Table[s=s+Prime[k], {k, 2, 15000000}], IntegerQ[Sqrt[#]]&]
Select[Accumulate[Prime[Range[2, 100000]]], IntegerQ[Sqrt[# ]]&] (* Harvey P. Dale, May 26 2023 *)
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PROG
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(PARI) s = 0; forprime(p=3, 1e10, s + = p; if (issquare(s), print1(s, ", ")))
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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