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 A137817 #14 Apr 04 2015 10:03:19 %S A137817 295569,295947,1586763,1811079,1964375,2069469,4473387,5854375, %T A137817 6820555,7285923,10936053,12233457,13260625,18029709,18052767, %U A137817 21153663,21576537,21604131,22182093,22877451,23744043,25536875,28340307,34102775 %N A137817 Cubeful "year numbers" (such that phi(n) = 2 phi(sigma(n)): A137815). %C A137817 See A137815 for general comments and references about "year numbers". This is the subsequence of cubeful elements of A137815, i.e. its intersection with A046099. As such, it is of course also a subsequence of A137816. %C A137817 There are only 56 such numbers below 10^8. %H A137817 M. F. Hasler and Donovan Johnson, <a href="/A137817/b137817.txt">Table of n, a(n) for n = 1..1000</a> (first 56 terms from _M. F. Hasler_) %o A137817 (PARI) for( i=1,#A137816, vecmax( factor( A137816[i] )[,2])>2 && print1(A137816[i]", ")) %o A137817 (PARI) for( i=1,#A046099, eulerphi(A046099[i])==2*eulerphi(sigma(A046099[i])) && print1( A046099[i] ", ")) %o A137817 (PARI) for( n=1,10^9, issquarefree(n) && next; vecmax(factor(n)[,2])>2 || next; eulerphi(n)==2*eulerphi(sigma(n)) && print1(n", ")) %Y A137817 Cf. A137815-A137819, A006872. A046099. A067704. %K A137817 nonn %O A137817 1,1 %A A137817 _R. K. Guy_, _R. J. Mathar_ and _M. F. Hasler_, Feb 11 2008