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A121658
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Primes neither of the n^2+1 nor n^2+n+1 form.
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2
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11, 19, 23, 29, 41, 47, 53, 59, 61, 67, 71, 79, 83, 89, 97, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 163, 167, 173, 179, 181, 191, 193, 199, 223, 227, 229, 233, 239, 251, 263, 269, 271, 277, 281, 283, 293, 311, 313, 317, 331, 337, 347, 349
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OFFSET
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1,1
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COMMENTS
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Previous name: Primes not equal to [k*(k or k+1 or k+2)] + 1 where k is a natural number.
Primes not of the form n^2 + 1 and n^2 + n + 1 and (n+1)^2. Correct version!!
Primes not contained in A200975 (numbers on the diagonals of Ulam's spiral). - Bob Selcoe, Oct 27 2014
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LINKS
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MATHEMATICA
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Select[Prime[Range[100]], NoneTrue[{Sqrt[#-1], (Sqrt[4#-3]-1)/2}, IntegerQ]&] (* The program uses the NoneTrue function from Mathematica version 10 *) (* Harvey P. Dale, Dec 23 2015 *)
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PROG
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(PARI) lista(nn) = {forprime(p=2, nn, if (!issquare(p-1) && !ispolygonal((p-1)/2, 3), print1(p, ", ")); ); } \\ Michel Marcus, Oct 28 2014
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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