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 A236056 Numbers n such that n^2 +/- n +/- 1 is prime for all four possibilities. 2
 3, 6, 21, 456, 1365, 2205, 2451, 2730, 8541, 18486, 32199, 32319, 32781, 45864, 61215, 72555, 72561, 82146, 83259, 86604, 91371, 95199, 125334, 149331, 176889, 182910, 185535, 210846, 225666, 226254, 288420, 343161, 350091, 403941, 411501, 510399, 567204 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The only prime in this sequence is a(1) = 3. LINKS EXAMPLE 1365^2+1365+1 (1864591), 1365^2-1365+1 (1861861), 1365^2+1365-1 (1864589), and 1365^2-1365-1 (1861859) are all prime. So 1365 is a member of this sequence. PROG (Python) import sympy from sympy import isprime {print(p) for p in range(10**6) if isprime(p**2+p+1) and isprime(p**2-p+1) and isprime(p**2+p-1) and isprime(p**2-p-1)} CROSSREFS Numbers in the intersection of A002384, A045546, A055494, and A002328. Sequence in context: A019054 A066986 A096662 * A280116 A295578 A054297 Adjacent sequences:  A236053 A236054 A236055 * A236057 A236058 A236059 KEYWORD nonn AUTHOR Derek Orr, Jan 18 2014 STATUS approved

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