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A056905
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Primes of the form k^2+5.
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7
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5, 41, 149, 1301, 2309, 5189, 6089, 9221, 13001, 15881, 26249, 28229, 39209, 41621, 60521, 66569, 86441, 112901, 116969, 138389, 171401, 186629, 207941, 213449, 242069, 254021, 266261, 285161, 304709, 331781, 345749, 352841, 389381, 443561
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Except for a(0), a(n) mod 180 = 41 or 149 since k must be a multiple of 6 without being a multiple of 30 for k^2+5 to be prime.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..1800
Eric Weisstein's World of Mathematics, Near-Square Prime
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FORMULA
| a(n) =36*A056906(n)+5
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EXAMPLE
| a(2)=149 since 12^2+5=149 which is prime
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MATHEMATICA
| Intersection[Table[n^2+5, {n, 0, 10^2}], Prime[Range[9*10^3]]] ...or... For[i=5, i<=5, a={}; Do[If[PrimeQ[n^2+i], AppendTo[a, n^2+i]], {n, 0, 100}]; Print["n^2+", i, ", ", a]; i++ ] - Vladimir Orlovsky (4vladimir(AT)gmail.com), Apr 29 2008
Select[Table[n^2+5, {n, 0, 7000}], PrimeQ] (* Vincenzo Librandi, Nov 30 2011 *)
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PROG
| (MAGMA) [a: n in [0..700] | IsPrime(a) where a is n^2+5]; // Vincenzo Librandi, Nov 30 2011
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CROSSREFS
| Cf. A002496, A056899, A049423, A005473.
Sequence in context: A142101 A102265 A128347 * A088547 A105412 A096946
Adjacent sequences: A056902 A056903 A056904 * A056906 A056907 A056908
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KEYWORD
| nonn,easy
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Jul 07 2000
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