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A302021
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Numbers k such that k^2+1, (k+2)^2+1 and (k+6)^2+1 are prime.
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2
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4, 14, 124, 204, 464, 1144, 1314, 1564, 1964, 2454, 3134, 4174, 4364, 5584, 5874, 6234, 7804, 8174, 8784, 9874, 9894, 10424, 12354, 12484, 12874, 14034, 14194, 15674, 16224, 18274, 18994, 21134, 21344, 22344, 22624, 23134, 23784, 23944, 24974, 25554, 26504, 26934, 27064, 27804, 29364
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OFFSET
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1,1
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LINKS
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MAPLE
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select(k->isprime(k^2+1) and isprime((k+2)^2+1) and isprime((k+6)^2+1), [$1..40000]); # Muniru A Asiru, Apr 02 2018
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MATHEMATICA
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Select[Range[1, 30000], PrimeQ[#^2 + 1] && PrimeQ[(# + 2)^2 + 1] && PrimeQ[(# + 6)^2 + 1] &] (* Vincenzo Librandi, Apr 02 2018 *)
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PROG
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(Python)
from python import isprime
k, klist, A302021_list = 0, [isprime(i**2+1) for i in range(6)], []
i = isprime((k+6)**2+1)
if klist[0] and klist[2] and i:
k += 1
(Magma) [n: n in [1..30000] | IsPrime(n^2+1) and IsPrime((n+2)^2+1) and IsPrime((n+6)^2+1)]; // Vincenzo Librandi, Apr 02 2018
(PARI) isok(k) = isprime(k^2+1) && isprime((k+2)^2+1) && isprime((k+6)^2+1); \\ Altug Alkan, Apr 02 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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