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Search: id:A003959
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| A003959 |
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If n = Product p(k)^e(k) then a(n) = Product (p(k)+1)^e(k), a(1) = 1. |
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+0
28
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| 1, 3, 4, 9, 6, 12, 8, 27, 16, 18, 12, 36, 14, 24, 24, 81, 18, 48, 20, 54, 32, 36, 24, 108, 36, 42, 64, 72, 30, 72, 32, 243, 48, 54, 48, 144, 38, 60, 56, 162, 42, 96, 44, 108, 96, 72, 48, 324, 64, 108, 72, 126, 54, 192, 72, 216, 80, 90, 60, 216, 62, 96, 128, 729, 84, 144, 68
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Completely multiplicative.
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LINKS
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Daniel Forgues, Table of n, a(n) for n=1..100000
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FORMULA
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If n = Product p(k)^e(k) then a(n) = Product (p(k)+1)^e(k), a(1) = 1.
Multiplicative with a(p^e) = (p+1)^e. - David W. Wilson (davidwwilson(AT)comcast.net), Aug 01, 2001.
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PROGRAM
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(PARI) a(n)=if(n<1, 0, direuler(p=2, n, 1/(1-X-p*X))[n]) (from R. Stephan)
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CROSSREFS
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Apart from initial terms, same as A064478. Cf. A003958.
Cf. A063441.
Adjacent sequences: A003956 A003957 A003958 this_sequence A003960 A003961 A003962
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KEYWORD
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nonn,easy,nice,mult,new
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AUTHOR
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Marc LeBrun (mlb(AT)well.com)
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EXTENSIONS
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Definition reedited (with formula) by Daniel Forgues (squid(AT)zensearch.com), Nov 17 2009
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