A161888 a(n) = the smallest positive integer that does not divide n, and is such that sum{k=1 to n} a(k) is coprime to n.
2, 3, 2, 6, 3, 7, 2, 6, 4, 4, 2, 8, 2, 4, 4, 6, 2, 4, 2, 6, 4, 4, 2, 14, 3, 3, 4, 8, 2, 4, 2, 6, 2, 4, 2, 8, 2, 4, 4, 6, 2, 4, 2, 6, 6, 4, 2, 10, 2, 4, 2, 6, 2, 4, 3, 3, 4, 4, 2, 8, 2, 4, 4, 6, 3, 5, 2, 6, 2, 8, 2, 10, 2, 4, 4, 6, 3, 9, 2, 6, 4, 4, 2, 8, 3, 3, 4, 6, 2, 4, 2, 6, 4, 4, 3, 5, 2, 4, 2, 8, 2, 8, 2, 6, 2
Offset: 1
Keywords
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Crossrefs
Cf. A161889
Programs
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Mathematica
spi[{n_,s_,a_}]:=Module[{k=1},While[Divisible[n+1,k]||!CoprimeQ[s+k, n+1], k++];{n+1,s+k,k}]; Transpose[NestList[spi,{1,2,2},105]][[3]] (* Harvey P. Dale, May 26 2015 *)
Extensions
More terms from Sean A. Irvine, Aug 10 2010
Comments