A206241 a(n) is the smallest number of the form k*a(n-1)+a(n-2) for k>0 that is relatively prime to n, with a(0) = 0 and a(1) = 1.

0, 1, 1, 2, 3, 8, 11, 19, 49, 68, 117, 185, 487, 672, 1159, 1831, 4821, 6652, 11473, 18125, 47723, 65848, 113571, 179419, 472409, 651828, 1124237, 1776065, 4676367, 6452432, 11128799, 17581231, 46291261, 63872492, 110163753, 284199998, 394363751, 678563749, 1751491249

Offset

0,4

Links

Table of n, a(n) for n=0..38.

Mathematica

nxt[{n_, a_, b_}]:=Module[{k=1}, While[!CoprimeQ[k*b+a, n+1], k++]; {n+1, b, k*b+a}]; NestList[nxt, {1, 0, 1}, 40][[;; , 2]] (* Harvey P. Dale, Jun 04 2023 *)

Prog

(PARI) ar(n)=local(r, m); r=vector(n); r[1]=0; r[2]=1; for(k=2, n-1, m=1; while(gcd(m*r[k]+r[k-1], k)>1, m++); r[k+1]=m*r[k]+r[k-1]); r

Crossrefs

Sequence in context: A112595 A041075 A041893 * A295333 A113873 A007676

Adjacent sequences: A206238 A206239 A206240 * A206242 A206243 A206244

Keyword

nonn

Author

Franklin T. Adams-Watters, Feb 05 2012

Status

approved