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 A259601 #17 Jul 31 2015 04:28:53
%S A259601 7,9,12,12,15,17,15,18,20,23,17,20,22,25,28,20,23,25,28,31,33,22,25,
%T A259601 27,30,33,35,38,25,28,30,33,36,38,41,43,28,31,33,36,39,41,44,46,49,30,
%U A259601 33,35,38,41,43,46,48,51,54,33,36,38,41,44,46,49,51,54,57
%N A259601 Triangular array: sums of two distinct upper Wythoff numbers.
%C A259601 Row n shows the numbers v(m) + v(n), where v = A001950 (upper Wythoff sequence), for m=1..n-1, for n >= 2. (The offset is 2, so that the top row is counted as row 2.)
%e A259601 17 = 7 + 10 = v(3) + v(4), so that 17 appears as the final term in row 4. (The offset is 2, so that the top row is counted as row 2.) Rows 2 to 9:
%e A259601 7
%e A259601 9 12
%e A259601 12 15 17
%e A259601 15 18 20 23
%e A259601 17 20 22 25 28
%e A259601 20 23 25 28 31 33
%e A259601 22 25 27 30 33 35 38
%e A259601 25 28 30 33 36 38 41 43
%t A259601 r = GoldenRatio; z = 13; v[n_] := v[n] = Floor[n*r^2];
%t A259601 s[m_, n_] := v[m] + v[n]; t = Table[s[m, n], {n, 2, z}, {m, 1, n - 1}]
%t A259601 TableForm[t] (* A259601 array *)
%t A259601 Flatten[t] (* A259601 sequence *)
%o A259601 (PARI) tabl(nn) = {r=(sqrt(5)+1)/2; for (n=2, nn, for (k=1, n-1, print1(floor(n*r^2) + floor(k*r^2), ", ");); print(););} \\ _Michel Marcus_, Jul 30 2015
%Y A259601 Cf. A000045, A001950, A259556, A259600.
%K A259601 nonn,tabl,easy
%O A259601 2,1
%A A259601 _Clark Kimberling_, Jul 22 2015