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!)
A067244 Numbers k such that phi(k) divides (sigma(k+1) + sigma(k-1)). 1

%I #12 Jun 02 2022 10:09:19

%S 2,3,4,6,32,34,54,55,58,70,84,133,141,221,285,322,377,407,472,664,684,

%T 988,1149,1241,1505,1911,1978,2230,2590,2631,2906,2912,3498,6111,6579,

%U 7232,8559,11194,13181,13952,15323,15409,15564,17362,18215,18754,22328

%N Numbers k such that phi(k) divides (sigma(k+1) + sigma(k-1)).

%H Amiram Eldar, <a href="/A067244/b067244.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[23000],Divisible[DivisorSigma[1,#-1]+DivisorSigma[1,#+1], EulerPhi[#]]&] (* _Harvey P. Dale_, Oct 04 2016 *)

%Y Cf. A000010, A000203.

%K easy,nonn

%O 1,1

%A _Benoit Cloitre_, Feb 20 2002

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 June 21 18:50 EDT 2024. Contains 373557 sequences. (Running on oeis4.)