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 A373341 #17 Jun 03 2024 18:21:19
%S A373341 1,2,1,6,4,1,24,216,16,1,120,331776,10077696,256,1,720,24883200000,
%T A373341 12116574790945106558976,1023490369077469249536,65536,1
%N A373341 Array read by ascending antidiagonals: A(n,k) is the number of acyclic de Bruijn sequences of order k and alphabet of size n, with k > 0.
%C A373341 The 7th antidiagonal is too large to be inserted in Data.
%H A373341 D. Condon, Yuxin Wang, and E. Yang, <a href="https://arxiv.org/abs/2405.18543">De Bruijn Polyominoes</a>, arXiv:2405.18543 [math.CO], 2024. See page 5.
%H A373341 T. van Aardenne-Ehrenfest and N. G. de Brujin, <a href="https://pure.tue.nl/ws/files/3311129/597493.pdf">Circuits and Trees in Oriented Linear Graphs</a>. In: Simon Stevin 28 (1951), pp. 203-217.
%F A373341 A(n,k) = (n!)^(n^(k-1)).
%F A373341 A(2,n) = A001146(n-1).
%e A373341 The array begins:
%e A373341 1, 1, 1, ...
%e A373341 2, 4, 16, ...
%e A373341 6, 216, 10077696, ...
%e A373341 24, 331776, 12116574790945106558976, ...
%e A373341 ...
%t A373341 A[n_,k_]:=(n!)^(n^(k-1)); Table[A[n-k+1,k],{n,6},{k,n}]//Flatten
%Y A373341 Cf. A000012 (n=1), A000142 (k=1), A001146, A003992, A036740 (k=2), A373342 (antidiagonal sums), A373343 (cyclic).
%K A373341 nonn,tabl
%O A373341 1,2
%A A373341 _Stefano Spezia_, Jun 01 2024