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 A234641 #10 Dec 29 2013 12:50:45 %S A234641 1,9,38423,104855,247863,313929,345807,376095,469623,623615,787127, %T A234641 943695,985369,1606281,1754039,1933815,2034423,2181409,3043401, %U A234641 5147241,5545617,5612535,6385703,7084143,8868321,10606679,11470511,11954409,12276745,12794655,13213921,14142695,15512065,15737953,15786351,16844135 %N A234641 Odd numbers n such that sigma(sigma(n^2)) is odd. %C A234641 The sum of divisors of a square is always odd, therefore these numbers have the property that x=n^2, y=sigma(x) and z=sigma(y) are all three odd. %C A234641 This is the subsequence of odd terms of A008847. %H A234641 M. F. Hasler, <a href="/A234641/b234641.txt">Table of n, a(n) for n = 1..122</a> %Y A234641 Cf. A000203, A000290, A008848, A163763. %K A234641 nonn %O A234641 1,2 %A A234641 _M. F. Hasler_, Dec 28 2013