cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A067193 Numbers k such that sigma(k) == 4 (mod phi(k)).

This page as a plain text file.
%I A067193 #27 Feb 11 2021 01:28:39
%S A067193 24,27,44,66,75,170,944,1200,16064,260864,4189184,17179541504,
%T A067193 274876596224
%N A067193 Numbers k such that sigma(k) == 4 (mod phi(k)).
%C A067193 a(14) > 10^12. 1125899822956544 and 4611686013058678784 are also terms. - _Donovan Johnson_, Feb 29 2012
%C A067193 a(14) > 10^13. If 2^j-5 is prime (A059608) and j > 3, then 2^(j-2)*(2^j-5) is a term. - _Giovanni Resta_, Mar 29 2020
%Y A067193 Cf. A063514, A059608, A067192.
%K A067193 nonn,more
%O A067193 1,1
%A A067193 _Benoit Cloitre_, Feb 19 2002
%E A067193 a(11) from _Donovan Johnson_, Dec 14 2009
%E A067193 a(12)-a(13) from _Donovan Johnson_, Feb 29 2012