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Search: id:A120939
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| A120939 |
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a(1)=1. a(n) = a(n-1) + (largest integer occurring among {a(1),a(2),a(3)..a(n-1)} which is coprime to n). |
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2
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| 1, 2, 4, 5, 9, 14, 23, 46, 92, 115, 230, 345, 690, 1035, 1127, 2254, 4508, 5635, 11270, 12397, 12627, 25254, 25268, 37665, 62933, 100598, 201196, 264129, 528258, 591191, 1182382, 1773573, 2955955, 5911910, 7685483, 15370966, 30741932, 38427415
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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Among the terms {a(1),a(2),a(3),a(4),a(5)}, a(4) = 5 is the largest term which is coprime to 6. So a(6) = a(5) + 5 = 14.
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MAPLE
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A120939 := proc(nmax) local a, cpr, n, i ; a := [1, 2] ; for n from 3 to nmax do cpr := 0 ; for i from 1 to n-1 do if gcd(n, a[i]) = 1 and a[i] > cpr then cpr := a[i] ; fi ; od ; a := [op(a), a[n-1]+cpr] ; od: RETURN(a) ; end: nmax := 100 : a := A120939(nmax) : for n from 1 to nops(a) do printf("%d, ", a[n]) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 17 2006
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PROGRAM
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(PARI) {m=38; print1(a=1, ", "); v=[a]; for(n=2, m, a=0; for(j=1, n-1, if(gcd(v[j], n)==1&&a<v[j], a=v[j])); print1(a=a+v[n-1], ", "); v=concat(v, a))} - (Klaus Brockhaus, Aug 16 2006)
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CROSSREFS
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Cf. A120938.
Sequence in context: A073153 A073154 A077882 this_sequence A120770 A073151 A067298
Adjacent sequences: A120936 A120937 A120938 this_sequence A120940 A120941 A120942
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Jul 17 2006
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EXTENSIONS
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More terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 16 2006
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 17 2006
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