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Search: id:A165320
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| A165320 |
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Primes p where neither the number of divisors of p+1 nor the number of divisors of p-1 is a power of 2. |
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+0
3
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| 17, 19, 97, 149, 163, 197, 199, 241, 293, 307, 337, 349, 449, 491, 523, 557, 577, 739, 773, 811, 881, 883, 991, 1013, 1051, 1061, 1151, 1171, 1249, 1277, 1279, 1423, 1451, 1459, 1471, 1493, 1531, 1549, 1601, 1637, 1667, 1693, 1709, 1733, 1747, 1861, 1949
(list; graph; listen)
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OFFSET
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1,1
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MAPLE
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isA000079 := proc(n) RETURN( n=1 or numtheory[factorset](n) = {2}) ; end: isA165320 := proc(n) RETURN ( isprime(n) and not isA000079(numtheory[tau](n-1)) and not isA000079(numtheory[tau](n+1)) ) ; end: for n from 1 to 10000 do if isA165320(n) then printf("%d, ", n) ; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 18 2009]
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MATHEMATICA
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fQ[n_] := Union[ IntegerQ@# & /@ Log[2, DivisorSigma[0, {n - 1, n + 1}]]] == {False}; Select[ Prime@ Range@ 300, fQ@# &] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 16 2009]
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CROSSREFS
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A165318, A165319
Sequence in context: A119768 A005808 A028489 this_sequence A132242 A068387 A134539
Adjacent sequences: A165317 A165318 A165319 this_sequence A165321 A165322 A165323
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Sep 14 2009
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com) and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 16 2009
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