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A290767
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Primes p such that p^2 +/- p +/- 1 are all nonprimes.
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0
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23, 37, 43, 73, 107, 109, 113, 137, 157, 179, 211, 223, 227, 229, 239, 251, 257, 271, 277, 283, 311, 313, 317, 347, 353, 367, 389, 439, 443, 467, 503, 509, 521, 523, 547, 557, 563, 577, 587, 593, 601, 631, 653, 661, 719, 733, 757, 797, 811, 821, 823, 829, 853, 859, 877, 883
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OFFSET
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1,1
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LINKS
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FORMULA
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MAPLE
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select(p -> isprime(p) and not ormap(isprime, [p^2+p+1, p^2+p-1, p^2-p+1, p^2-p-1]), [2, seq(i, i=3..1000, 2)]); # Robert Israel, Aug 10 2017
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MATHEMATICA
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Select[Prime[Range[1000]], ! (PrimeQ[#^2 + # + 1] || PrimeQ[#^2 + # - 1] ||PrimeQ[#^2 - # + 1] || PrimeQ[#^2 - # - 1]) &]
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PROG
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(PARI) is(n) = my(v=[n^2+n+1, n^2+n-1, n^2-n+1, n^2-n-1]); for(k=1, #v, if(ispseudoprime(v[k]), return(0))); 1
forprime(p=1, 900, if(is(p), print1(p, ", "))) \\ Felix Fröhlich, Aug 10 2017
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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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