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Search: id:A097974
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| A097974 |
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Sum of distinct prime divisors of n which are <= sqrt(n). |
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+0
4
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| 0, 0, 0, 2, 0, 2, 0, 2, 3, 2, 0, 5, 0, 2, 3, 2, 0, 5, 0, 2, 3, 2, 0, 5, 5, 2, 3, 2, 0, 10, 0, 2, 3, 2, 5, 5, 0, 2, 3, 7, 0, 5, 0, 2, 8, 2, 0, 5, 7, 7, 3, 2, 0, 5, 5, 9, 3, 2, 0, 10, 0, 2, 10, 2, 5, 5, 0, 2, 3, 14, 0, 5, 0, 2, 8, 2, 7, 5, 0, 7, 3, 2, 0, 12, 5, 2, 3, 2, 0, 10, 7, 2, 3, 2, 5, 5, 0, 9, 3, 7, 0, 5, 0
(list; graph; listen)
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OFFSET
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1,4
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EXAMPLE
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2 and 3 are the distinct prime divisors of 12, and both 2 and 3 are <= squareroot of 12. So a(12) = 2 + 3 = 5.
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MAPLE
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with(numtheory): a:=proc(n) local s, F, f, i: s:=0: F:=factorset(n): f:=nops(F): for i from 1 to f do if F[i]^2<=n then s:=s+F[i] else s:=s: fi od: s; end: seq(a(n), n=1..110); (Deutsch) (Deutsch)
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MATHEMATICA
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Do[Print[Plus @@ Select[Select[Divisors[n], PrimeQ], #<=Sqrt[n] &]], {n, 1, 100}] (Propper)
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CROSSREFS
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Adjacent sequences: A097971 A097972 A097973 this_sequence A097975 A097976 A097977
Sequence in context: A140302 A085341 A063918 this_sequence A139036 A090330 A132747
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Sep 07 2004
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EXTENSIONS
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More terms from Ryan Propper (rpropper(AT)stanford.edu), Jul 23 2005
Further terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 30 2006
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