

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



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
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Sum{k=1 to n} a(k) = A161889(n).


LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000


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 *)


CROSSREFS

Cf. A161889
Sequence in context: A134060 A329282 A197289 * A157224 A097914 A286633
Adjacent sequences: A161885 A161886 A161887 * A161889 A161890 A161891


KEYWORD

nonn


AUTHOR

Leroy Quet, Jun 21 2009


EXTENSIONS

More terms from Sean A. Irvine, Aug 10 2010


STATUS

approved



