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Search: id:A061286
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| A061286 |
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Smallest integer for which the number of divisors is the n-th prime. |
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+0
20
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| 2, 4, 16, 64, 1024, 4096, 65536, 262144, 4194304, 268435456, 1073741824, 68719476736, 1099511627776, 4398046511104, 70368744177664, 4503599627370496, 288230376151711744, 1152921504606846976
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Seems to be the same as "Even numbers with prime number of divisors" - Jason Earls (zevi_35711(AT)yahoo.com), Jul 04 2001
Except for the first term, smallest number == 1 (mod prime(n)) having n divisors (by Fermat's little theorem). - Amarnath Murthy and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), Jun 20 2003
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FORMULA
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a(n) = 2^[p(n)-1] = Min{k| A000005(k) = prime} = 2^A006093(n).
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PROGRAM
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(PARI) forstep(n=2, 100000000, 2, x=numdiv(n); if(isprime(x), print(n)))
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CROSSREFS
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Cf. A000040, A000005, A005179, A003680, A061283, A061286, A006093, A005097, A006254.
Sequence in context: A154001 A154004 A060656 this_sequence A019279 A061652 A162119
Adjacent sequences: A061283 A061284 A061285 this_sequence A061287 A061288 A061289
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), May 22 2001
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