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 A355854 #44 Jul 31 2022 19:53:27 %S A355854 4,9,16,20,25,35,36,49,54,56,60,64,77,80,81,91,99,100,104,108,110,121, %T A355854 128,135,136,140,143,144,154,156,169,170,171,176,180,182,187,189,195, %U A355854 196,209,216,220,221,224,225,240,250,252,256,260,266,270,272,275,286,289 %N A355854 Numbers of the form (ab+cd)*(ad+bc) with integers a,b,c,d >= 1. %H A355854 David A. Corneth, <a href="/A355854/b355854.txt">Table of n, a(n) for n = 1..10000</a> %e A355854 77 is in the sequence because (1*1+2*5)(1*5+1*2)=77 (for a=1, b=1, c=2, d=5). %Y A355854 Cf. A000290. %K A355854 nonn %O A355854 1,1 %A A355854 _Thomas Kerscher_, Jul 30 2022 %E A355854 More terms from _David A. Corneth_, Jul 30 2022