login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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
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
Sequence in context: A134060 A329282 A197289 * A347859 A157224 A097914
KEYWORD
nonn
AUTHOR
Leroy Quet, Jun 21 2009
EXTENSIONS
More terms from Sean A. Irvine, Aug 10 2010
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 21:55 EDT 2024. Contains 371254 sequences. (Running on oeis4.)