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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).
2
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
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
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