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 A115011 #13 Oct 08 2018 03:49:10
%S A115011 0,2,2,4,12,4,6,26,26,6,8,44,56,44,8,10,66,98,98,66,10,12,92,148,172,
%T A115011 148,92,12,14,122,210,262,262,210,122,14,16,156,280,376,400,376,280,
%U A115011 156,16,18,194,362,502,578,578,502,362,194,18,20,236,452,652,772,836,772,652,452,236,20
%N A115011 Array read by antidiagonals: let V(m,n) = Sum_{i=1..m, j=1..n, gcd(i,j)=1} (m+1-i)*(n+1-j), then T(m,n) = 2*(2*m*n+m+n+2*V(m,n)), for m >= 0, n >= 0.
%H A115011 Max A. Alekseyev. <a href="http://arXiv.org/abs/math.CO/0602511">On the number of two-dimensional threshold functions</a>. SIAM J. Disc. Math. 24(4), 2010, pp. 1617-1631. doi:10.1137/090750184
%t A115011 V[m_, n_] := Sum[If[GCD[i, j] == 1, (m-i+1)(n-j+1), 0], {i, m}, {j, n}];
%t A115011 T[m_, n_] := 2(2m n + m + n + 2 V[m, n]);
%t A115011 Table[T[m-n, n], {m, 0, 10}, {n, 0, m}] // Flatten (* _Jean-François Alcover_, Oct 08 2018 *)
%Y A115011 Twice A115009, which see for further information.
%K A115011 nonn,tabl
%O A115011 0,2
%A A115011 _N. J. A. Sloane_, Feb 24 2006