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A107758
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(+2)Sigma(n) : If n=Product p_i^r_i then (+2)Sigma(n)=Product (2+Sum p_i^s_i, s_i=1 to r_i)=Product(1+(p_i^(r_i+1)-1)/(p_i-1)), (+2)Sigma(1)=1.
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2
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1, 4, 5, 8, 7, 20, 9, 16, 14, 28, 13, 40, 15, 36, 35, 32, 19, 56, 21, 56, 45, 52, 25, 80, 32, 60, 41, 72, 31, 140, 33, 64, 65, 76, 63, 112, 39, 84, 75, 112, 43, 180, 45, 104, 98, 100, 49, 160, 58, 128, 95, 120, 55, 164
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| (+2)Sigma(6)=(2+2)*(2+3)=20.
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MAPLE
| A107758 := proc(n) local pf, p ; if n = 1 then 1; else pf := ifactors(n)[2] ; mul( 1+(op(1, p)^(op(2, p)+1)-1)/(op(1, p)-1), p=pf) ; end if; end proc:
seq(A107758(n), n=1..60) ; # R. J. Mathar, Jan 07 2011
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CROSSREFS
| Cf. A107759, A052396.
Sequence in context: A020804 A021222 A132023 * A104883 A154885 A042956
Adjacent sequences: A107755 A107756 A107757 * A107759 A107760 A107761
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KEYWORD
| nonn,mult
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AUTHOR
| Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp), May 25 2005
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