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 A038688 #16 Aug 12 2024 04:26:04 %S A038688 1,4,36,121,144,256,324,400,576,784,900,961,1024,1296,1600,1764,1936, %T A038688 2304,2704,2916,3136,3600,3844,4096,4356,4624,4900,5184,5776,6084, %U A038688 6400,7056,7744,8100,9216,9604,10000,10404,10816,11664,12544,12996,14400 %N A038688 Squares that are the sum of the divisors of some number. %H A038688 Amiram Eldar, <a href="/A038688/b038688.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from T. D. Noe) %H A038688 Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts#Inversion_of_Multiplicative_Functions">PARI/GP Scripts for Miscellaneous Math Problems: Inversion of Multiplicative Functions</a> (invphi.gp). %F A038688 a(n) = A228061(n)^2. - _Amiram Eldar_, Aug 12 2024 %t A038688 nn = 14400; t = Select[Union[DivisorSigma[1, Range[nn]]], IntegerQ[Sqrt[#]] &]; t = Select[t, # <= nn &] (* _T. D. Noe_, Sep 04 2013 *) %o A038688 (PARI) lista(kmax) = for(k = 1, kmax, if(invsigmaNum(k^2) > 0, print1(k^2, ", "))); \\ _Amiram Eldar_, Aug 12 2024, using _Max Alekseyev_'s invphi.gp %Y A038688 Intersection of A000290 and A002191. %Y A038688 Cf. A000203, A006532, A228061. %K A038688 nonn %O A038688 1,2 %A A038688 _David W. Wilson_