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 A162880 #5 Jun 25 2013 14:00:58 %S A162880 2,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27, %T A162880 28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,45,46,47,48,50,51,52, %U A162880 53,54,55,56,57,58,59,60,61,62,63,64,65,67,69,71,72,73,74,75,77,78,79,80 %N A162880 Numbers k such that tau(sigma(k)) is not equal to sigma(tau(k)). %C A162880 The complement of A076361, that is, the indices k where A076360(k) is not zero. %e A162880 a(6)= 8 is in the list because tau(sigma(8))=A062068(8)=4 whereas sigma(tau(8)) = A062069(8) = 7. %o A162880 (PARI) is(n)=numdiv(sigma(n))!=sigma(numdiv(n)) \\ _Charles R Greathouse IV_, Jun 25 2013 %Y A162880 Cf. A000005, A000203, A076361, A076360. %K A162880 nonn %O A162880 1,1 %A A162880 _Jaroslav Krizek_, Jul 16 2009 %E A162880 Edited by _R. J. Mathar_, Jul 21 2009