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A065985
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Numbers n such that d(n) / 2 is prime, where d(n) = number of divisors of n.
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1
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6, 8, 10, 12, 14, 15, 18, 20, 21, 22, 26, 27, 28, 32, 33, 34, 35, 38, 39, 44, 45, 46, 48, 50, 51, 52, 55, 57, 58, 62, 63, 65, 68, 69, 74, 75, 76, 77, 80, 82, 85, 86, 87, 91, 92, 93, 94, 95, 98, 99, 106, 111, 112, 115, 116, 117, 118, 119, 122, 123, 124, 125, 129, 133, 134
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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MATHEMATICA
| Select[Range[1, 1000], PrimeQ[DivisorSigma[0, # ] / 2] == True &]
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PROG
| (PARI) { n=0; for (m=1, 10^9, f=numdiv(m)/2; if (frac(f)==0 && isprime(f), write("b065985.txt", n++, " ", m); if (n==1000, return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Nov 05 2009]
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CROSSREFS
| Sequence in context: A064176 A000379 A176525 * A060652 A020739 A064466
Adjacent sequences: A065982 A065983 A065984 * A065986 A065987 A065988
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Dec 10 2001
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