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A090693
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Positive numbers n such that n^2 - 2n + 2 is a prime.
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7
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2, 3, 5, 7, 11, 15, 17, 21, 25, 27, 37, 41, 55, 57, 67, 75, 85, 91, 95, 111, 117, 121, 125, 127, 131, 135, 147, 151, 157, 161, 171, 177, 181, 185, 205, 207, 211, 225, 231, 237, 241, 251, 257, 261, 265, 271, 281, 285, 301, 307, 315, 327, 341, 351, 385, 387, 397
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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REFERENCES
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M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988
Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta,UTET, CittaStudiEdizioni, Milano 1997
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LINKS
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FORMULA
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MATHEMATICA
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a={}; Do[If[PrimeQ[n^2-2n+2], AppendTo[a, n]], {n, 1000}]; a (* Peter J. C. Moses, Apr 02 2013 *)
Select[Range[400], PrimeQ[#^2-2#+2]&] (* Harvey P. Dale, May 10 2013 *)
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PROG
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(Python)
# Python 3.2 or higher required.
from itertools import accumulate
from sympy import isprime
A090693_list = [i for i, n in enumerate(accumulate(range(10**5), lambda x, y:x+2*y-3)) if i > 0 and isprime(n+2)] # Chai Wah Wu, Sep 23 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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