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).

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

Links

Table of n, a(n) for n=1..38.

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

Adjacent sequences: A120936 A120937 A120938 * A120940 A120941 A120942

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