A265670 Numbers n such that n^5 + n^4 + n^3 + n^2 + n - 1 is prime.
2, 8, 10, 12, 16, 18, 22, 24, 28, 32, 42, 50, 60, 68, 70, 78, 88, 104, 108, 118, 132, 138, 206, 238, 240, 242, 270, 282, 300, 306, 312, 318, 338, 372, 376, 382, 390, 394, 398, 418, 440, 452, 464, 512, 522, 532, 534, 548, 566, 586, 594, 626, 630, 636, 640, 650
Offset: 1
Examples
2 is in the sequence because 2^5 + 2^4 + 2^3 + 2^2 + 2 - 1 = 61 is prime.
Programs
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Magma
[n: n in [0..700] | IsPrime(s) where s is n^5+n^4+n^3+n^2+n-1];
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Mathematica
Select[Range[700], PrimeQ[Total[#^Range[1, 5, 1]] - 1] &]
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PARI
print1(2, ", "); forcomposite(n=1, 1e4, if(ispseudoprime(n^5 + n^4 + n^3 + n^2 + n - 1), print1(n, ", "))) \\ Altug Alkan, Dec 13 2015
Comments