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Search: id:A079138
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| A079138 |
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Primes of the form n^2+7. |
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+0
1
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| 7, 11, 23, 43, 71, 107, 151, 263, 331, 491, 683, 907, 1031, 1163, 1303, 1451, 1607, 2311, 2711, 3371, 3607, 3851, 4363, 5483, 5783, 6091, 10007, 11243, 12107, 13003, 13463, 13931, 14407, 14891, 15383, 17431, 18503, 19051, 20743, 21323, 21911
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The sum of the reciprocals converges to 0.350314... Are there infinitely many primes of this form?
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MATHEMATICA
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Intersection[Table[n^2+7, {n, 0, 10^2}], Prime[Range[9*10^3]]] ...or... For[i=7, i<=7, a={}; Do[If[PrimeQ[n^2+i], AppendTo[a, n^2+i]], {n, 0, 100}]; Print["n^2+", i, ", ", a]; i++ ] - Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 29 2008
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PROGRAM
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(PARI) nsqpm(n) = {sr=0; forstep(x=0, n, 2, y = x*x+7; if(isprime(y), print1(y" "); sr+=1.0/y; ); ); print(); print(sr); } \\ Primes of the form n^2 + 7 and the sum of the reciprocals.
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CROSSREFS
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Sequence in context: A089056 A082496 A107133 this_sequence A163848 A111671 A140111
Adjacent sequences: A079135 A079136 A079137 this_sequence A079139 A079140 A079141
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Dec 26 2002
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