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Search: id:A065061
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| A065061 |
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Numbers n such that sigma(n) - tau(n) is a prime. |
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+0
3
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| 3, 8, 162, 512, 1250, 8192, 31250, 32768, 41472, 663552, 2531250, 3748322, 5120000, 6837602, 7558272, 8000000, 15780962, 33554432, 35701250, 42762752, 45334242, 68024448, 75031250, 78125000, 91125000, 137149922, 243101250, 512000000
(list; graph; listen)
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OFFSET
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1,1
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MATHEMATICA
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Do[ If[ PrimeQ[ DivisorSigma[1, n] - DivisorSigma[0, n]], Print[n]], {n, 1, 10^7}]
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PROGRAM
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(PARI) { n=0; for (m=1, 10^9, if (isprime(sigma(m) - numdiv(m)), write("b065061.txt", n++, " ", m); if (n==100, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 05 2009]
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CROSSREFS
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I.e. A065608(n) is prime. Cf. A064205.
Sequence in context: A053605 A076147 A132563 this_sequence A007159 A081466 A092592
Adjacent sequences: A065058 A065059 A065060 this_sequence A065062 A065063 A065064
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Nov 06 2001
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EXTENSIONS
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a(17) - a(28) from Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 05 2009
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