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Search: id:A138353
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| A138353 |
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Primes of the form n^2+9. |
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+0 1
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| 13, 73, 109, 409, 1033, 1453, 1609, 2713, 3373, 3853, 4909, 6733, 7753, 9613, 10009, 12109, 12553, 13933, 19609, 20173, 25609
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is easy to show that n mod 12 must be 2,4,8,10 and that since n^2 mod 12 = 4, then p mod 12 = 1. In base 12, the sequence is 11, 61, 91, 2X1, 721, X11, E21, 16X1, 1E51, 2291, 2X11, 3X91, 45X1, 5691, 5961, 7011, 7321, 8091, E421, E811, 129X1, where X is for 10, E is for 11. Keep in mind that 12 is a canonical base for mathematics in general since any prime greater than 3 is of the form 6k+-1, any prime of the form 4k+1 is a sum of squares while any prime of the form 4k+3 is never a sum of squares and lcm(6,4)=12. - Walter A. Kehowski (wkehowski(AT)cox.net), May 31 2008
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MATHEMATICA
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Intersection[Table[n^2+9, {n, 0, 10^2}], Prime[Range[9*10^3]]] ...or... For[i=9, i<=9, a={}; Do[If[PrimeQ[n^2+i], AppendTo[a, n^2+i]], {n, 0, 100}]; Print["n^2+", i, ", ", a]; i++ ]
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CROSSREFS
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Sequence in context: A139849 A139911 A097460 this_sequence A097402 A139873 A142787
Adjacent sequences: A138350 A138351 A138352 this_sequence A138354 A138355 A138356
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), May 07 2008
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