A163463 a(1)=1. For n >= 2: If a(n-1) is coprime to n, then a(n) = the smallest integer > a(n-1) that is coprime to n. If a(n-1) is not coprime to n, then a(n) = the smallest integer > a(n-1) that is not coprime to n.

1, 3, 6, 8, 9, 10, 11, 13, 14, 15, 16, 18, 19, 23, 26, 28, 29, 31, 32, 34, 37, 39, 40, 42, 43, 45, 48, 49, 50, 51, 52, 54, 55, 57, 58, 60, 61, 63, 65, 66, 67, 71, 72, 74, 76, 78, 79, 83, 85, 86, 88, 90, 91, 95, 99, 101, 103, 105, 106, 108, 109, 111, 112, 114, 116, 117, 118

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..1000

Mathematica

a = {1}; Do[If[GCD[n, a[[ -1]]] == 1, k = a[[ -1]] + 1; While[GCD[k, n] > 1, k++ ]; AppendTo[a, k], k = a[[ -1]] + 1; While[GCD[k, n] < 2, k++ ]; AppendTo[a, k]], {n, 2, 100}]; a (* Stefan Steinerberger, Aug 05 2009 *)

Prog

(PARI) al(n)=local(v, q); v=vector(n); v[1]=1; for(k=2, n, q=gcd(k, v[k-1])!=1; v[k]=v[k-1]+1; while(gcd(k, v[k])!=1!=q, v[k]++)); v \\ Franklin T. Adams-Watters, Aug 06 2009

Crossrefs

Sequence in context: A350618 A133159 A188544 * A137386 A358510 A344952

Adjacent sequences: A163460 A163461 A163462 * A163464 A163465 A163466

Keyword

nonn

Author

Leroy Quet, Jul 28 2009

Extensions

More terms from Stefan Steinerberger and Franklin T. Adams-Watters, Aug 05 2009

Status

approved