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 A015705 #13 Oct 02 2017 10:54:42 %S A015705 1,51,105,405,477,595,679,1023,1455,1463,1485,1715,1731,2651,2945, %T A015705 3135,3567,4381,5797,5859,8245,8255,8721,9639,9809,10127,10153,10179, %U A015705 10295,11935,12369,17765,17955,19125,19875,20195,20213,20273 %N A015705 Geometric mean of phi(n) and sigma(n) is an integer, n odd. %H A015705 Donovan Johnson, <a href="/A015705/b015705.txt">Table of n, a(n) for n = 1..10000</a> %H A015705 Richard K. Guy, <a href="http://www.jstor.org/stable/2974586">Divisors and desires</a>, Amer. Math. Monthly, 104 (1997), 359-360. %o A015705 (PARI) isok(n) = (n%2) && issquare(sigma(n)*eulerphi(n)); \\ _Michel Marcus_, Oct 02 2017 %Y A015705 Cf. A011257. %K A015705 nonn %O A015705 1,2 %A A015705 _Robert G. Wilson v_ %E A015705 Offset corrected by _Donovan Johnson_, Jan 18 2012