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Search: id:A112636
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| A112636 |
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Numbers n such that sigma(2^n+3^n) is divisible by n. |
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+0
1
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| 1, 2, 3, 14, 24, 28, 48, 72, 84, 132, 140, 144, 154, 155, 165, 180, 192, 196
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Cf. A114705 = sum of divisors of 2^n + 3^n, A000203 sigma(n) = sum of divisors of n, A007689 2^n + 3^n.
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FORMULA
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n | sigma(2^n+3^n)
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EXAMPLE
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14 is OK because 2^14+3^14 = 4799353 with divisors {1,13,369181,4799353} sum of which is 5168548=14*369182.
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PROGRAM
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(PARI) for(x=1, 200, if(sigma(2^x+3^x)%x==0, print1(x, ", "))) -Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Feb 15 2006
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CROSSREFS
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Cf. A000203, A007689, A114705.
Sequence in context: A024603 A089876 A025092 this_sequence A124663 A101005 A029998
Adjacent sequences: A112633 A112634 A112635 this_sequence A112637 A112638 A112639
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KEYWORD
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more,nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Dec 27 2005
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EXTENSIONS
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3 more terms from Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Feb 15 2006
More terms from Ryan Propper (rpropper(AT)stanford.edu), Jan 09 2007
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