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Search: id:A097957
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| A097957 |
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Primes p such that p divides 5^(p-1)/2 + 4^(p-1)/2. |
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+0
1
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| 3, 7, 13, 17, 23, 37, 43, 47, 53, 67, 73, 83, 97, 103, 107, 113, 127, 137, 157, 163, 167, 173, 193, 197, 223, 227, 233, 257, 263, 277, 283, 293, 307, 313, 317, 337, 347, 353, 367, 373, 383, 397, 433, 443, 457, 463, 467, 487, 503, 523, 547, 557, 563, 577, 587
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Also odd primes congruent to {2, 3} mod 5, or primes with last digit 3 or 7. - Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 02 2006
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FORMULA
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a(n) = A003631(n-1). - Alexander Adamchuk (alex(AT)kolmogorov.com), Nov 02 2006
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EXAMPLE
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5^3 + 4^3 = 7*27
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PROGRAM
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(PARI) \s = +-1, d=diff ptopm1d2(n, x, d, s) = { forprime(p=3, n, p2=(p-1)/2; y=x^p2 + s*(x-d)^p2; if(y%p==0, print1(p", "))) }
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CROSSREFS
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Cf. A003631 = Primes congruent to {2, 3} mod 5.
Sequence in context: A034914 A034913 A040148 this_sequence A071774 A019403 A045422
Adjacent sequences: A097954 A097955 A097956 this_sequence A097958 A097959 A097960
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KEYWORD
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nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Sep 06 2004
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