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 A120939 a(1)=1. a(n) = a(n-1) + (largest integer occurring among {a(1),a(2),a(3),...,a(n-1)} that is coprime to n). 2

%I

%S 1,2,4,5,9,14,23,46,92,115,230,345,690,1035,1127,2254,4508,5635,11270,

%T 12397,12627,25254,25268,37665,62933,100598,201196,264129,528258,

%U 591191,1182382,1773573,2955955,5911910,7685483,15370966,30741932,38427415

%N a(1)=1. a(n) = a(n-1) + (largest integer occurring among {a(1),a(2),a(3),...,a(n-1)} that is coprime to n).

%e 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.

%p 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_, Aug 17 2006

%o (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

%Y Cf. A120938.

%K nonn

%O 1,2

%A _Leroy Quet_, Jul 17 2006

%E More terms from _Klaus Brockhaus_, Aug 16 2006

%E More terms from _R. J. Mathar_, Aug 17 2006

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Last modified October 14 04:29 EDT 2019. Contains 327995 sequences. (Running on oeis4.)