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A100484
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Even semiprimes.
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45
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4, 6, 10, 14, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 178, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482, 502, 514, 526
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Essentially the same as A001747.
Twice the prime numbers. - Omar E. Pol, May 14 2008
An alternative sequence that gives A100484 functionally: a(n)=Length[IntegerDigits[(2^Prime[n] - 1)*(2^Prime[n] + 1), 2]]. Roger L. Bagula and Artur Jasinski, Nov 28 2008
Semiprimes of the form m*k such that m/(k-1)=prime. [From Juri-Stepan Gerasimov, May 21 2010]
Right edge of the triangle in A065342. [Reinhard Zumkeller, Jan 30 2012]
Solutions of the differential equation n'=1/2*(n+4), where n' is the arithmetic derivative of n. - Paolo P. Lava, Feb 02 2012.
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LINKS
| Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Semiprime
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FORMULA
| a(n) = 2 * A000040(n).
n>1: A000005(a(n))=4; A000203(a(n))=3*A008864(n); A000010(a(n))=A006093(n); intersection of A001358 and A005843.
a(n) = A116366(n-1,n-1) for n>1. - Reinhard Zumkeller, Feb 06 2006
a(n)=A077017(n+1), n>1. [From R. J. Mathar, Sep 02 2008]
A078834(a(n)) = A000040(n). [Reinhard Zumkeller, Sep 19 2011]
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MATHEMATICA
| Prime[Range[22]]*2 - Vladimir Orlovsky, Apr 29 2008
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PROG
| (PARI) 2*primes(100) \\ Charles R Greathouse IV, Aug 21 2011
(Haskell)
a100484 n = a100484_list !! (n-1)
a100484_list = map (* 2) a000040_list
-- Reinhard Zumkeller, Jan 31 2012
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CROSSREFS
| Cf. A046315, a(n)=A001747(n+1).
Cf. A152099.
Cf. A179740. [From Reinhard Zumkeller, Jul 25 2010]
Sequence in context: A137860 A184335 A091376 * A076924 A103801 A141247
Adjacent sequences: A100481 A100482 A100483 * A100485 A100486 A100487
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KEYWORD
| nonn,easy,changed
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 22 2004
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