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 A176978 Numbers n such that n^2 + 13 and n^2 + 13^2 are primes. 5
 2, 10, 12, 28, 42, 60, 68, 108, 110, 122, 142, 180, 198, 200, 268, 282, 340, 378, 380, 418, 430, 488, 500, 502, 530, 612, 742, 788, 802, 838, 840, 912, 942, 948, 952, 1010, 1080, 1102, 1148, 1232, 1270, 1428, 1452, 1472, 1502, 1522, 1538, 1720, 1778, 1830 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers are subsequence of A113536 and A176969 See comments and references of A176969 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 EXAMPLE 2^2 + 13 = 17 = prime(7), 2^2 + 13^2 = 173 = prime(40), 2 is first term. MATHEMATICA Select[Range[2000], AllTrue[#^2+{13, 13^2}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 28 2015 *) PROG (PARI) isok(n) = isprime(n^2 + 13) && isprime(n^2 + 13^2); \\ Michel Marcus, Aug 27 2013 CROSSREFS Cf. A000040, A000290, A056899, A113536, A176371, A176969. Sequence in context: A004686 A080139 A055701 * A186630 A154391 A035928 Adjacent sequences:  A176975 A176976 A176977 * A176979 A176980 A176981 KEYWORD nonn AUTHOR Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Apr 30 2010 STATUS approved

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Last modified August 14 19:09 EDT 2020. Contains 336483 sequences. (Running on oeis4.)