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A078138
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Primes which can be written as sum of squares > 1.
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4
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13, 17, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311
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OFFSET
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1,1
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COMMENTS
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By Sylvester's solution to the Frobenius problem, all integers greater than 4*9 - 4 - 9 = 23 can be represented as a sum of multiples of 4 and 9. Hence all primes except 2,3,5,7,11,19,23 are in this sequence. [Charles R Greathouse IV, Apr 19 2010]
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LINKS
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EXAMPLE
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A000040(11) = 31 = 3^2 + 3^2 + 3^2 + 2^2, therefore 31 is a term.
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MATHEMATICA
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Join[{13, 17}, Prime[Range[10, 100]]] (* Harvey P. Dale, May 12 2014 *)
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PROG
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(PARI) a(n)=if(n<3, [13, 17][n], prime(n+7))
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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