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A276556
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a(n) = smallest prime p such that (smallest prime > p^2) == p^2 + 4n^2, n>=1.
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0
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5, 281, 461, 4937, 25367, 75997, 1193909, 3464389, 48591863, 23674667, 22486333, 1648510979, 12708853771, 25139472583, 53498475287
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OFFSET
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1,1
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LINKS
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EXAMPLE
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5^2+4*1^2=29, 281^2+4*2^2=78977, 461^2 + 4*3^2=212557 (all prime).
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MATHEMATICA
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Table[p = 2; While[NextPrime[p^2] != p^2 + 4 n^2, p = NextPrime@ p]; p, {n, 8}] (* Michael De Vlieger, Apr 22 2017 *)
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PROG
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(PARI) a(n) = {forprime(p=2, , if (nextprime(p^2+1) == p^2 + 4*n^2, return (p)); ); } \\ Michel Marcus, Apr 19 2017
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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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