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 A160320 #12 Aug 27 2014 01:14:17 %S A160320 3,12,234,1080,6048,6552,435708,4713984,18506880,36197280,275890944, %T A160320 299980800,4138364160,13286744064,17827568640,30600708096, %U A160320 459010621440,2198278051200,2567400675840,3321402084000,4959751305600,295185198672000,1217745604232064 %N A160320 Numbers n for which sigma(n)/n = k+1/3 with integer k. %e A160320 a(1)=3 since sigma(3)/3=(1+3)/3=1+1/3. %e A160320 a(2)=12 since sigma(12)/12=(1+2+3+4+6+12)/12=28/12=7/3=2+1/3. %o A160320 (PARI) is(n)=denominator(sigma(n,-1)-1/3)==1 \\ _Charles R Greathouse IV_, Mar 09 2014 %Y A160320 Cf. A160321 (sigma(n)/n=k+2/3), A159907 (sigma(n)/n=k+1/2). %K A160320 nonn %O A160320 1,1 %A A160320 J.C. Klein (hklein(AT)planet.nl), May 08 2009 %E A160320 a(11)-a(16) from _Donovan Johnson_, May 26 2009 %E A160320 a(17)-a(23) from _Michel Marcus_, Sep 21 2012