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A156226
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Primes of the form 9n^2 + 1
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0
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37, 577, 1297, 2917, 4357, 7057, 8101, 14401, 15877, 22501, 24337, 32401, 41617, 44101, 57601, 69697, 72901, 90001, 93637, 147457, 156817, 176401, 197137, 224677, 324901, 331777, 352837, 404497, 427717, 476101, 484417, 509797, 562501
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 9n^2 + 1 can be a prime only for n's of the form n=10m or n=10m+-2.
Primes in this sequence must end with 1 or 7 and will have to be 1 modulo 30 or 7 modulo 30.
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EXAMPLE
| a(5) = 4357 = 9*22^2 + 1
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MATHEMATICA
| Union[Select[9#^2+1&/@Flatten[Table[{10m, 10m+2, 10m-2}, {m, 0, 50}]], PrimeQ]]
[From Harvey P. Dale, Dec. 16, 2010]
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PROG
| (MAGMA)[a: n in [0..250]|IsPrime(a) where a is 9*n^2+1][From Vincenzo Librandi, Dec 13 2010]
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CROSSREFS
| Sequence in context: A142764 A123035 A006303 * A133998 A056217 A105464
Adjacent sequences: A156223 A156224 A156225 * A156227 A156228 A156229
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KEYWORD
| nonn
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AUTHOR
| Avik Roy (avik_3.1416(AT)yahoo.co.in), Feb 06 2009
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EXTENSIONS
| Corrected, extended, comments added by Rick L. Shepherd and Zak Seidov, Feb 08 2009
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