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 A090758 #10 Mar 05 2020 04:14:10 %S A090758 5,13,15,17,19,24,29,37,44,45,46,47,61,73,75,85,86,87,99,105,107,144, %T A090758 145,149,171,173,186,187,197,203,205,224,245,252,270,272,276,279,282, %U A090758 284 %N A090758 Numbers k which occur exactly twice in A001600. %H A090758 T. Goto and S. Shibata, <a href="http://dx.doi.org/10.1090/S0025-5718-03-01554-0">All numbers whose positive divisors have integral harmonic mean up to 300</a>, Math. Comput. 73 (2004), 475-491. %e A090758 k = 61 is a term because m*tau(m)/sigma(m) = 61 if and only if m = 2^30 * 61 * (2^31-1) or m = 2^60 * (2^61-1). - _Jinyuan Wang_, Mar 05 2020 %Y A090758 Cf. A001600, A090240. %K A090758 nonn,more %O A090758 1,1 %A A090758 _R. K. Guy_, Feb 08 2004