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 A239287 #22 May 23 2025 23:46:14 %S A239287 0,0,0,1,0,1,1,0,0,1,2,1,0,1,2,2,1,0,0,1,2,3,2,1,0,1,2,3,3,2,1,0,0,1, %T A239287 2,3,4,3,2,1,0,1,2,3,4,4,3,2,1,0,0,1,2,3,4,5,4,3,2,1,0,1,2,3,4,5,5,4, %U A239287 3,2,1,0,0,1,2,3,4,5,6,5,4,3,2,1,0,1,2 %N A239287 Triangle T(n,k), 0 <= k <= n, read by rows: T(n,k) = floor(n/2) - min(k,n-k). %C A239287 Row sums are A110660(n). %H A239287 G. C. Greubel, <a href="/A239287/b239287.txt">Rows, n=0..100 of triangle, flattened</a> %F A239287 T(n,k) = floor(n/2) - min(k,n-k). %e A239287 Triangle begins: %e A239287 0; %e A239287 0, 0; %e A239287 1, 0, 1; %e A239287 1, 0, 0, 1; %e A239287 2, 1, 0, 1, 2; %e A239287 2, 1, 0, 0, 1, 2; %e A239287 3, 2, 1, 0, 1, 2, 3; %e A239287 3, 2, 1, 0, 0, 1, 2, 3; %e A239287 4, 3, 2, 1, 0, 1, 2, 3, 4; %e A239287 4, 3, 2, 1, 0, 0, 1, 2, 3, 4; %e A239287 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5; %e A239287 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5; %e A239287 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6; %e A239287 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6; %e A239287 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7; %e A239287 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7; %e A239287 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8; %e A239287 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8; %e A239287 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9; %e A239287 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9; %t A239287 Column[Table[Floor[n/2] - Min[k, n - k], {n,0, 19}, {k, 0, n}]] (* _Indranil Ghosh_, Mar 15 2017 *) %o A239287 (PARI) tabl(nn) = {for(n=0, nn, for(k=0, n, print1(floor(n/2) - min(k, n - k),", ");); print(););}; %o A239287 tabl(19); \\ _Indranil Ghosh_, Mar 15 2017 %o A239287 (Python) %o A239287 i=0 %o A239287 for n in range(0,20): %o A239287 for k in range(0, n+1): %o A239287 print(str(i)+" "+str((n//2) - min(k, n - k))) %o A239287 i+=1 # _Indranil Ghosh_, Mar 15 2017 %o A239287 (Magma) [[Floor(n/2) - Min(k,n-k): k in [0..n]]: n in [0..10]]; // _G. C. Greubel_, May 26 2018 %Y A239287 Cf. A004526. %K A239287 nonn,tabl %O A239287 0,11 %A A239287 _Philippe Deléham_, Mar 14 2014