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Search: id:A141565
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| A141565 |
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Add 1 to all bases and exponents which are greater than 1 in the prime number decomposition of n. |
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+0
1
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| 2, 3, 4, 27, 6, 12, 8, 81, 64, 18, 12, 108, 14, 24, 24, 243, 18, 192, 20, 162, 32, 36, 24, 324, 216, 42, 256, 216, 30, 72, 32, 729, 48, 54, 48, 1728, 38, 60, 56, 486, 42, 96, 44, 324, 384, 72, 48, 972, 512, 648, 72, 378, 54, 768, 72, 648, 80, 90, 60, 648, 62, 96, 512
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Start from the prime number decomposition of n, that is the list 1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3... Add 1 to all visible bases and exponents (visible in the sense that exponents are not written down if they equal 1), that is 1+1, 2+1, 3+1, (2+1)^(2+1), 5+1, (2+1)*(3+1), 7+1, (2+1)^(3+1), (3+1)^(2+1), (2+1)*(5+1), 11+1, (2+1)^(2+1)*(3+1)..). Evaluate this modified product to yield a(n).
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MAPLE
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A := proc(n) local a, p, e, q, ifs ; ifs := ifactors(n)[2] ; if n = 1 then RETURN(2) fi; a := 1; for p in ifs do q := op(1, p)+1 ; if op(2, p) > 1 then e := op(2, p)+1 ; else e := 1 ; fi; a := a*q^e ; od: RETURN(a) ; end: for n from 1 to 120 do printf("%d, ", A(n)) ; od: # R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 21 2008
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CROSSREFS
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Cf. A000040, A002808.
Sequence in context: A043309 A104386 A044906 this_sequence A098549 A100604 A062931
Adjacent sequences: A141562 A141563 A141564 this_sequence A141566 A141567 A141568
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Aug 14 2008
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EXTENSIONS
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Edited and corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 21 2008
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