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 A386640 #11 Jul 30 2025 23:38:21
%S A386640 1,225,270,1900,4988,5656,6120,8704,11180,16588,17710,19228,24475,
%T A386640 28449,29458,32330,34606,38088,39292,40221,41181,42476,48545,48640,
%U A386640 53795,56832,57288,64975,78793,84925,86242,117116,124135,128478,129673,134044,136224,136896,147149,150528,168055,183141
%N A386640 Numbers k such that k + A224787(k) is a square.
%C A386640 Numbers k such that the sum of k and the cubes of the prime factors of k, counted with multiplicity, is a square.
%H A386640 Robert Israel, <a href="/A386640/b386640.txt">Table of n, a(n) for n = 1..3000</a>
%e A386640 a(3) = 270 = 2 * 3^3 * 5 is a term because 270 + 2^3 + 3 * 3^3 + 5^3 = 484 = 22^2 is a square.
%p A386640 filter:= proc(n) local t;
%p A386640 issqr(n + add(t[1]^3*t[2],t=ifactors(n)[2]))
%p A386640 end proc:
%p A386640 select(filter, [$1..10^6]);
%t A386640 lim=184000;f[{p_,e_}]:=e*p^3;a224787[k_]:=If[k==1,0,Total[f/@FactorInteger[k]]];q[k_]:=IntegerQ[Sqrt[k+a224787[k]]];Select[Range[lim],q[#]&] (* _James C. McMahon_, Jul 30 2025 *)
%Y A386640 Cf. A224787, A385238, A386246, A386257, A386623.
%K A386640 nonn
%O A386640 1,2
%A A386640 _Will Gosnell_ and _Robert Israel_, Jul 27 2025