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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
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
OFFSET
1,2
EXAMPLE
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.
MAPLE
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
PROG
(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
CROSSREFS
Cf. A120938.
Sequence in context: A351293 A363225 A234273 * A213290 A277852 A277854
KEYWORD
nonn
AUTHOR
Leroy Quet, Jul 17 2006
EXTENSIONS
More terms from Klaus Brockhaus, Aug 16 2006
More terms from R. J. Mathar, Aug 17 2006
STATUS
approved