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 A216705 #26 Aug 17 2025 03:50:55
%S A216705 1,72,5508,429624,33832890,2679564888,213025408596,16981168285224,
%T A216705 1356370816782267,108509665342581360,8691624193940766936,
%U A216705 696910230823250585232,55927046023565859464868,4491372003738673637024784,360913821729000560118063000
%N A216705 a(n) = Product_{k=1..n} (81 - 9/k).
%C A216705 This sequence is generalizable: Product_{k=1..n} (q^2 - q/k) = (q^n/n!) * Product_{k=0..n-1} (q*k + q-1) = expansion of (1- x*q^2)^((1-q)/q).
%H A216705 Harvey P. Dale, <a href="/A216705/b216705.txt">Table of n, a(n) for n = 0..524</a>
%F A216705 From _Amiram Eldar_, Aug 17 2025: (Start)
%F A216705 a(n) = 81^n * Gamma(n+8/9) / (Gamma(8/9) * Gamma(n+1)).
%F A216705 a(n) ~ c * 81^n / n^(1/9), where c = 1/Gamma(8/9) = 0.927851... . (End)
%p A216705 seq(product(81-9/k, k=1.. n), n=0..20);
%p A216705 seq((9^n/n!)*product(9*k+8, k=0.. n-1), n=0..20);
%t A216705 Table[Product[81-9/k,{k,n}],{n,0,20}] (* _Harvey P. Dale_, Jul 20 2021 *)
%Y A216705 Cf. A004988, A049382, A004994, A216702, A216703, A216704.
%K A216705 nonn
%O A216705 0,2
%A A216705 _Michel Lagneau_, Sep 16 2012