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.
%I A066995 #35 Dec 09 2024 10:12:10 %S A066995 1,6,15,28,84,95,140,182,190,248,270,287,308,357,420,455,477,496,570, %T A066995 672,744,819,840,910,1199,1428,1488,1547,1638,1722,1848,1892,2295, %U A066995 2398,2480,2660,2730,3339,3417,3472,3515,3596,3640,3720,3780,3956,4064,4095 %N A066995 Numbers k such that sigma(k) divides k*phi(k). %H A066995 Harry J. Smith, <a href="/A066995/b066995.txt">Table of n, a(n) for n = 1..1000</a> %t A066995 Select[Range[4500],Divisible[# EulerPhi[#],DivisorSigma[1,#]]&] (* _Harvey P. Dale_, Mar 19 2011 *) %o A066995 (PARI) isok(n) = frac(n*eulerphi(n)/sigma(n)) == 0; \\ _Michel Marcus_, Jan 31 2018 %o A066995 (GAP) Filtered([1..10^5], n -> n*Phi(n) mod Sigma(n) = 0); # _Muniru A Asiru_, Jan 31 2018 %Y A066995 Cf. A001599, A011775. %K A066995 nonn %O A066995 1,2 %A A066995 _Benoit Cloitre_, Jan 27 2002