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 A380436 #10 Mar 21 2025 20:37:03
%S A380436 12,16,32,36,48,60,80,81,96,108,112,120,128,140,144,168,192,220,224,
%T A380436 240,252,256,288,300,320,336,351,360,364,396,400,420,432,448,480,486,
%U A380436 500,512,528,540,544,560,576,588,608,612,624,625,640,644,648,660,672,704
%N A380436 Integers with at least 1 proper factorization for which the sum of the squares of the factors is a square.
%H A380436 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a380/A380436.java">Java program</a> (github)
%e A380436 a(1) = 12: {3, 4} (3 * 4 = 12 and 3^2 + 4^2 = 5^2).
%e A380436 a(2) = 16: {2, 2, 2, 2} (2 * 2 * 2 * 2 = 16 and 2^2 + 2^2 + 2^2 + 2^2 = 4^2).
%e A380436 a(3) = 32: {2, 4, 4} (2 * 4 * 4 = 32 and 2^2 + 4^2 + 4^2 = 6^2).
%o A380436 (PARI) a380436_count(x, f=List())={my(r=x/if(#f, vecprod(Vec(f)), 1)); if(r==1, return(if(issquare(sum(i=1, #f, f[i]^2)), 1, 0))); my(d, c=0); fordiv(r, d, if(d==1 || d==x || (#f && d<f[#f]), next); listput(f, d); c+=a380436_count(x, f); listpop(f)); return(c)} \\ _Charles L. Hohn_, Mar 09 2025
%Y A380436 A118903 is a subsequence.
%K A380436 nonn
%O A380436 1,1
%A A380436 _Charles L. Hohn_, Jan 24 2025