|
%I #11 Jun 25 2021 18:00:38
%S 6,25,48,60,98,150,192,304,336,896,990,800,1248,1232,1210,1105,1798,
%T 2448,2790,4032,5166,5095,7488,8925,9798,8484,12540,12528,14448,14112,
%U 15994,12950,19998,21312,21222,24198,12288,35768,26560,33792,46620
%N a(n)=phi(n^2+1)/n if (n^2+1) is composite and phi(n^2+1)==0 (mod n).
%C If n^2+1 is prime, trivially phi(n^2+1)/n=n.
%H Harvey P. Dale, <a href="/A067926/b067926.txt">Table of n, a(n) for n = 1..100</a>
%t cep[n_]:=Module[{c=n^2+1,ep},ep=EulerPhi[c];If[CompositeQ[c] && Mod[ ep,n] == 0,ep/n,Nothing]]; Array[cep,47000] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 25 2021 *)
%Y Cf. A066820.
%K easy,nonn
%O 1,1
%A _Benoit Cloitre_, Feb 22 2002
|
