Search: id:A129912
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%I A129912
%S A129912 1,2,6,12,30,60,180,210,360,420,1260,2310,2520,4620,6300,12600,13860,
%T A129912 27720,30030,37800,60060,69300,75600,138600,180180,360360,415800,485100,
%U A129912 510510,831600,900900,970200,1021020,1801800,2910600,3063060,5405400
%N A129912 Numbers that are products of distinct primorial numbers (see A002110).
%D A129912 CRC Standard Mathematical Tables, 28th Ed., CRC Press
%H A129912 T. D. Noe, <a href="b129912.txt">Table of n, a(n) for n=1..1000</a>
%H A129912 Robert Potter, <a href="http://primorialconjecture.org/default.aspx">
               Perfect Numbers</a>.
%H A129912 J. Sokol, <a href="http://www.dnull.com/~sokol/prime/conjecture1.html">
               Title?</a>
%H A129912 Wikipedia, <a href="http://en.wikipedia.org/wiki/Primorials">Primorials</
               a>
%H A129912 Wikimedia Commons,<a href="http://commons.wikimedia.org/wiki/File:OEIS_A129912_spin1.svg">
               Normalized A129912</a>
%F A129912 Apart from 1 and 2, numbers of the form 2^k(1)*3^k(2)*5^k(3)*...*p(s)^k(s), 
               where p(s) is s-th prime, k(i)>0 for i=1..s, k(i)-k(i-1) = 0 or 1 
               for i=2..s and |{k(1),k(2),..,k(s)}|=k(1). - Vladeta Jovovic (vladeta(AT)eunet.rs), 
               Jun 14 2007
%e A129912 For s = 4 there are 8 (generally 2^(s-1)) such numbers: 210 = 2*3*5*7, 
               420 = 2^2*3*5*7 = (2*3*5*7)*2, 1260 = 2^2*3^2*5*7 = (2*3*5*7)*(2*3), 
               6300 = 2^2*3^2*5^2*7 = (2*3*5*7)*(2*3*5), 2520 = 2^3*3^2*5*7 = (2*3*5*7)*(2*3)*2, 
               12600 = 2^3*3^2*5^2*7 = (2*3*5*7)*(2*3*5)*2, 37800 = 2^3*3^3*5^2*7 
               = (2*3*5*7)*(2*3*5)*(2*3), 75600 = 2^4*3^3*5^2*7 = (2*3*5*7)*(2*3*5)*(2*3)*2.
%Y A129912 Cf. A002110, A025487.
%Y A129912 Sequence in context: A166456 A162214 A100071 this_sequence A161507 A032177 
               A095349
%Y A129912 Adjacent sequences: A129909 A129910 A129911 this_sequence A129913 A129914 
               A129915
%K A129912 easy,nonn
%O A129912 1,2
%A A129912 Bill McEachen (bmceache(AT)centralsan.dst.ca.us), Jun 05 2007, Jun 06 
               2007, Jul 06 2007, Aug 07 2007
%E A129912 Edited by N. J. A. Sloane (njas(AT)research.att.com), Jun 09 2007, Aug 
               08 2007
%E A129912 I corrected the Potter link to reflect its relocation Bill McEachen (bmceache(AT)centralsan.org), 
               Sep 12 2009
%E A129912 I added link to Wikicommons image Bill McEachen (bmceache(AT)centralsan.org), 
               Sep 16 2009

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