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Search: id:A117893
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| A117893 |
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Add up the positive integers which are coprime to n in order (starting at 1). a(n) is the smallest such partial sum that is >= n. |
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+0
5
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| 1, 4, 3, 4, 6, 6, 10, 9, 12, 11, 15, 13, 15, 18, 22, 16, 21, 24, 21, 20, 30, 25, 28, 24, 31, 36, 27, 29, 36, 32, 36, 36, 37, 36, 44, 37, 45, 49, 48, 44, 45, 47, 45, 53, 46, 49, 55, 54, 59, 61, 61, 68, 55, 54, 65, 57, 61, 64, 66, 68, 66, 64, 70, 64, 77, 85, 78, 83, 75, 73, 78, 73
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(2) = 1+3. Every other a(n) of the sequence involves only adding integers which are <= n.
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EXAMPLE
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12 is coprime to 1, 5, 7, 11,... Now 1 = 1, 1+5 = 6, 1+5+7 = 13, 1+5+7+11 = 24, ... 13 is the smallest such partial sum that is >= 12. So a(12) = 13.
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MAPLE
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printf("1, 4, ") ; for n from 3 to 60 do resul :=0 ; for m from 1 to 1000 do if gcd(n, m) <= 1 then resul := resul + m ; if resul >= n then printf("%a, ", resul) ; break ; fi ; fi ; od : od: - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 02 2006
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MATHEMATICA
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f[n_] := Block[{k = 1, s}, While[s = Plus @@ Select[Range[k], GCD[ #, n] == 1 &]; s < n, k++ ]; s]; Table[f[n], {n, 75}] (*Chandler*)
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CROSSREFS
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Cf. A117892, A125748, A125749.
Cf. A092933.
Sequence in context: A090369 A132293 A135103 this_sequence A021701 A097511 A021027
Adjacent sequences: A117890 A117891 A117892 this_sequence A117894 A117895 A117896
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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), Mar 30 2006
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 02 2006
a(61) and later terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Dec 11 2006
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