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 A361475 #8 Mar 14 2023 09:32:06
%S A361475 0,1,0,3,1,0,7,4,1,0,15,13,5,1,0,31,40,21,6,1,0,63,121,85,31,7,1,0,
%T A361475 127,364,341,156,43,8,1,0,255,1093,1365,781,259,57,9,1,0,511,3280,
%U A361475 5461,3906,1555,400,73,10,1,0,1023,9841,21845,19531,9331,2801,585,91,11,1,0
%N A361475 Array read by ascending antidiagonals: A(n, k) = (k^n - 1)/(k - 1), with k >= 2.
%F A361475 E.g.f. of column k: exp(x)*(exp((k-1)*x) - 1)/(k - 1).
%F A361475 E.g.f. of column k: 2*exp((k+1)*x/2)*sinh((k-1)*x/2)/(k - 1).
%F A361475 A(n, k) = Sum_{i=0..n-1} k^i.
%e A361475 The array begins:
%e A361475 0, 0, 0, 0, 0, ...
%e A361475 1, 1, 1, 1, 1, ...
%e A361475 3, 4, 5, 6, 7, ...
%e A361475 7, 13, 21, 31, 43, ...
%e A361475 15, 40, 85, 156, 259, ...
%e A361475 ...
%t A361475 A[n_,k_]:=(k^n-1)/(k-1); Flatten[Table[A[n-k+2,k],{n,0,10},{k,2,n+2}]]
%Y A361475 Cf. A003992, A361291 (k=2*n+1), A361476 (antidiagonal sums).
%Y A361475 Cf. A000225 (k=2), A003462 (k=3), A002450 (k=4), A003463 (k=5), A003464 (k=6), A023000 (k=7), A023001 (k=8), A002452 (k=9), A002275 (k=10), A016123 (k=11).
%K A361475 nonn,tabl
%O A361475 0,4
%A A361475 _Stefano Spezia_, Mar 13 2023