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 A121826 #17 Jan 07 2021 06:55:30
%S A121826 11,242,7986,351384,19326120,1275523920,98215341840,8642950081920,
%T A121826 855652058110080,864208578691180800,960135730925901868800,
%U A121826 1163684505882193064985600,1527917756223319494326092800,2160475707299773764977095219200,3273120696559157253940299257088000
%N A121826 a(n) = Product_{k=1..n} D(k), where D() are the doublets, A020338.
%C A121826 a(n) is divisible by n! because D(k) is divisible by k. - _Michel Marcus_, Jan 07 2021
%e A121826 a(4)=351384 because 11*22*33*44 = 351384.
%o A121826 (PARI) D(n) = eval(Str(n, n)); \\ A020338
%o A121826 a(n) = prod(k=1, n, D(k)); \\ _Michel Marcus_, Jan 07 2021
%Y A121826 Cf. A000142, A020338.
%K A121826 easy,base,nonn
%O A121826 1,1
%A A121826 _Jason Earls_, Aug 27 2006