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 A382597 #6 Mar 31 2025 22:02:14
%S A382597 1,1,8,105,3840,181545,15814656,1635491025,261144576000,
%T A382597 47396578806225,12046266925056000,3390530144534798265,
%U A382597 1256223498048110592000,506594307608708171477625,257699484814807738928332800,140934799049120316306629726625,94240120920042785192632469422080
%N A382597 a(n) = Product_{i=1..n} 1 - i + n*(n - i + 1) - (n - 2*i + 1)*((n - i + 1) mod 2).
%C A382597 a(n) is the product of the elements of the main antidiagonal of the n X n square matrix M(n) formed by writing the numbers 1, ..., n^2 successively forward and backward along the rows in zig-zag pattern (see A317614).
%C A382597 Except for n = 0, 2, and 6, a(n) has trailing zeros iff n is even.
%e A382597 a(4) = 3840:
%e A382597 1, 2, 3, 4;
%e A382597 8, 7, 6, 5;
%e A382597 9, 10, 11, 12;
%e A382597 16, 15, 14, 13.
%t A382597 a[n_]:=Product[1-i+n(n-i+1)-(n-2i+1)Mod[n-i+1,2],{i,n}]; Array[a,17,0]
%Y A382597 Cf. A317614, A370753, A382532.
%K A382597 nonn
%O A382597 0,3
%A A382597 _Stefano Spezia_, Mar 31 2025