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1, 2, 6, 7, 13, 17, 25, 26, 39, 45, 57, 61, 75, 83, 107, 108, 126, 139, 159, 165, 197, 209, 233, 237, 268, 282, 322, 330, 360, 384, 416, 417, 465, 483, 531, 544, 582, 602, 658, 664, 706, 738, 782, 794, 872, 896, 944, 948, 1005, 1036, 1108, 1122, 1176, 1216
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| The subsequence of primes begins: 2, 7, 13, 17, 61, 83, 107, 139, 197, 233, then no more through a(54). [From Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 14 2010]
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LINKS
| M. Baake and R. V. Moody, Similarity submodules and root systems in four dimensions, Canad. J. Math. 51 (1999), 1258-1276.
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FORMULA
| a(n)=sum(k=1, n, A000593(k)); a(n) is asymptotic to c*n^2 where c=Pi^2/24
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PROG
| (PARI) a(n)=sum(v=1, n, sumdiv(v, d, (-1)^(d+1)*v/d))
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CROSSREFS
| Sequence in context: A072147 A190121 A124319 * A127406 A092310 A087376
Adjacent sequences: A078468 A078469 A078470 * A078472 A078473 A078474
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Dec 31 2002
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