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!)
 A015833 Numbers k such that phi(k + 13) | sigma(k). 1

%I #23 Aug 31 2018 02:53:38

%S 5,7,15,21,23,35,47,71,77,87,132,155,191,263,295,297,310,357,359,428,

%T 431,437,479,503,527,595,638,660,719,759,790,837,839,863,983,1002,

%U 1105,1151,1155,1223,1269,1336,1376,1463,1495,1511,1512,1559,1615,1817,1871

%N Numbers k such that phi(k + 13) | sigma(k).

%H Vincenzo Librandi, <a href="/A015833/b015833.txt">Table of n, a(n) for n = 1..2000</a>

%t Select[Range[3000], Divisible[DivisorSigma[1, #], EulerPhi[13 + #]] &] (* _David Nacin_, Mar 03 2012 *)

%o (PARI) is(n)=sigma(n)%(eulerphi(n)+13)==0 \\ _Charles R Greathouse IV_, Sep 25 2012

%K nonn

%O 1,1

%A _Robert G. Wilson v_

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 20 11:25 EDT 2024. Contains 372712 sequences. (Running on oeis4.)