A120938 a(0)=1. a(n) = a(n-1) + (largest integer occurring among {a(0),a(1),a(2),...,a(n-1)} that is coprime to n).

1, 2, 3, 5, 10, 13, 26, 52, 65, 130, 143, 273, 416, 426, 569, 1138, 1707, 3414, 3983, 7966, 11949, 13087, 26174, 38123, 76246, 152492, 190615, 381230, 571845, 1143690, 1181813, 2325503, 4651006, 9302012, 11627515, 20929527, 32557042, 65114084

Offset

0,2

Links

Table of n, a(n) for n=0..37.

Example

Among the terms {a(0),a(1),a(2),a(3),a(4),a(5)}, a(5) = 13 is the largest term that is coprime to 6. So a(6) = a(5) + 13 = 26.

Maple

A120938 := 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-1, 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 := A120938(nmax) : for n from 1 to nops(a) do printf("%d, ", a[n]); od; # R. J. Mathar, Aug 17 2006

Prog

(PARI) {m=37; print1(a=1, ", "); v=[a]; for(n=1, m, a=0; for(j=1, n, if(gcd(v[j], n)==1&&a<v[j], a=v[j])); print1(a=a+v[n], ", "); v=concat(v, a))} \\ Klaus Brockhaus, Aug 16 2006

Crossrefs

Cf. A120939.

Sequence in context: A103746 A071848 A268176 * A120610 A090859 A004681

Adjacent sequences: A120935 A120936 A120937 * A120939 A120940 A120941

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