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 A377642 #42 Nov 16 2024 14:57:54
%S A377642 1,2,12,224,13440,2666496,1791885312,4161269661696,33955960439439360,
%T A377642 987107315743488737280,103404624282172311371513856,
%U A377642 39408968779516596852827017445376,55084280201257118417007491904448757760,284322478318511376197290687371005495020093440
%N A377642 a(n) = (1/(n-1)!) * Product_{i=1..n-1} (2^n-2^i).
%H A377642 Nikita Babich, <a href="/A377642/b377642.txt">Table of n, a(n) for n = 1..100</a>
%F A377642 a(n) = (Product_{i=1..n-1}(2^n-2^i))/((n-1)!).
%F A377642 a(n) = A028365(n-1)/A000142(n-1).
%F A377642 a(n) = A000079(n-1) * A053601(n-1).
%F A377642 a(n) ~ A048651 * 2^(n*(n-1)) / (n-1)!. - _Vaclav Kotesovec_, Nov 13 2024
%t A377642 Table[Product[2^n - 2^i, {i, 1, n - 1}]/Factorial[n - 1], {n, 1, 20}]
%o A377642 (PARI) a(n)=prod(i=1, n-1, 2^n-2^i)/(n-1)! \\ _Andrew Howroyd_, Nov 10 2024
%Y A377642 Appears to be main diagonal of A270882.
%Y A377642 Cf. A000079, A000142, A002884, A028365, A048651, A053601.
%K A377642 nonn,easy
%O A377642 1,2
%A A377642 _Nikita Babich_, Nov 05 2024