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 A278868 #17 Aug 08 2025 05:00:03
%S A278868 1,1,6183,5772211367657472,76148812142946816440318638031477145600000,
%T A278868 3940613226283843476344831941863494501303228636304800836707599745608602091520000000000
%N A278868 Second series of Hankel determinants based on hyperfactorial/4.
%C A278868 It would be useful to know the formula for this sequence.
%p A278868 a:= n-> LinearAlgebra[Determinant](Matrix(n, (i, j)->
%p A278868 (t-> mul(k^k, k=0..t)/4)(i+j))):
%p A278868 seq(a(n), n=0..6); # _Alois P. Heinz_, Nov 29 2016
%t A278868 Table[Det[Table[Hyperfactorial[i + j]/4, {i, n}, {j, n}]], {n, 6}]
%Y A278868 Cf. A002109, A277829, A278770, A278860.
%K A278868 nonn
%O A278868 0,3
%A A278868 _Karol A. Penson_, Nov 29 2016