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 A049621 #8 Dec 16 2019 22:09:57
%S A049621 0,1,4,8,12,18,24,30,38,48,56,66,76,86,102,118,128,142,156,170,192,
%T A049621 214,228,246,268,288,312,338,356,380,404,422,452,484,514,550,576,598,
%U A049621 634,674,700,732,764,790,836,882,908,942,982,1020,1070,1118,1148,1186,1238,1286,1340,1392,1424,1470,1516
%N A049621 a(n) = T(n,n+1), array T as in A049615.
%H A049621 G. C. Greubel, <a href="/A049621/b049621.txt">Table of n, a(n) for n = 0..1000</a>
%t A049621 T[n_, k_]:= Length[Select[Flatten[Table[{x, y}, {x,0,n}, {y,0,k}], 1], GCD @@ # > 1 &]]; Table[T[n, n+1], {n,0,65}] (* _G. C. Greubel_, Dec 16 2019 *)
%Y A049621 Cf. A049615, A049616, A049617, A049618, A049619, A049620, A049622, A049623.
%K A049621 nonn
%O A049621 0,3
%A A049621 _Clark Kimberling_
%E A049621 Terms a(37) onward added by _G. C. Greubel_, Dec 16 2019