The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A015870 Numbers k such that phi(k + 4) | sigma(k) + 4. 0
 6, 11, 12, 62, 65, 166, 251, 782, 2342, 6662, 25040, 83623931, 933180002, 943169410, 1840122962, 4294967291 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS There are no other terms < 4290000000. - Jud McCranie, Dec 26 1999 a(17) > 10^12. - Donovan Johnson, Feb 28 2012 LINKS Table of n, a(n) for n=1..16. EXAMPLE phi(6+4)=4, which divides 16=sigma(6)+4, so 6 is a term of the sequence. MATHEMATICA Select[Range[100000], Divisible[DivisorSigma[1, #] + 4, EulerPhi[# + 4]] &] (* David Nacin, Feb 28 2012 *) PROG (PARI) is(n)=(sigma(n)+4)%eulerphi(n+4)==0 \\ Charles R Greathouse IV, Jan 29 2016 CROSSREFS Cf. A000010, A000203. Sequence in context: A212773 A230996 A219553 * A004471 A175021 A315367 Adjacent sequences: A015867 A015868 A015869 * A015871 A015872 A015873 KEYWORD nonn,more AUTHOR Robert G. Wilson v EXTENSIONS a(16) from Donovan Johnson, Feb 28 2012 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.

Last modified May 26 08:37 EDT 2024. Contains 372814 sequences. (Running on oeis4.)