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Search: id:A065387
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| 2, 4, 6, 9, 10, 14, 14, 19, 19, 22, 22, 32, 26, 30, 32, 39, 34, 45, 38, 50, 44, 46, 46, 68, 51, 54, 58, 68, 58, 80, 62, 79, 68, 70, 72, 103, 74, 78, 80, 106, 82, 108, 86, 104, 102, 94, 94, 140, 99, 113, 104, 122, 106, 138, 112, 144, 116, 118, 118, 184, 122, 126, 140
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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a(n) = 2n for n listed in A008578, the prime numbers at the beginning of the 20th century. When a(n) = a(n + 1), n is probably listed in A066198, numbers n where EulerPhi changes as fast as sigma (the only exceptions below 10000 are 2 and 854). - Alonso Delarte (alonso.delarte(AT)gmail.com), Nov 16 2005
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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EXAMPLE
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a(10) = 22 because there are 4 coprimes to 10 below 10, the divisors of 10 add up to 18, and 4 + 18 = 22.
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MATHEMATICA
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Table[EulerPhi[n] + (Plus @@ Divisors[n]), {n, 65}] (Delarte)
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CROSSREFS
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a(n) = A000203[n] + A000010[n].
Cf. A000010, A000203, A065388, A015702, A051709.
A051709(n) + 2n.
Sequence in context: A138972 A050110 A003661 this_sequence A065388 A024978 A085148
Adjacent sequences: A065384 A065385 A065386 this_sequence A065388 A065389 A065390
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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), Nov 05 2001
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