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 A163983 #10 Jan 24 2023 12:34:06 %S A163983 1,6,18,41,77,133,210,310,445,602,810,1049,1347,1693,2068,2545,3028, %T A163983 3613,4256,4987,5817,6711,7640,8783,9962,11157,12454,13992,15615, %U A163983 17310,19194,21113,23108,25325,27852,30412,33158,36019,38920,41877,45230,48686,52528,56593,60399,64406 %N A163983 Antidiagonal sums of A163280. %o A163983 (PARI) lista(nn) = my(v = apply(f, [1..nn^2]), cols = vector(nn, i, select(x->(x==i), v, 1))); vector(nn, i, sum(j=1, i, cols[j][i-j+1])); \\ _Michel Marcus_, Jan 23 2023 %Y A163983 Cf. A163280, A161344, A164000. %K A163983 nonn %O A163983 1,2 %A A163983 _Omar E. Pol_, Aug 08 2009 %E A163983 More terms from _Michel Marcus_, Jan 23 2023 %E A163983 Definition corrected by _Omar E. Pol_, Jan 24 2023