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 A052278 #11 Feb 25 2022 04:25:51
%S A052278 6,1260,2494800,20432412000,475176173472000,25246110096567360000,
%T A052278 2658415393168543008000000,501882242076289234480320000000,
%U A052278 157671325170687025904337331200000000,77811744999685071405945898971187200000000,57616484702466807973246700352205274112000000000
%N A052278 a(n) = (4n+3)!/4^n.
%F A052278 From _Amiram Eldar_, Feb 25 2022: (Start)
%F A052278 Sum_{n>=0} 1/a(n) = (sinh(sqrt(2)) - sin(sqrt(2)))/(4*sqrt(2)).
%F A052278 Sum_{n>=0} (-1)^n/a(n) = (cosh(1)*sin(1) - sinh(1)*cos(1))/4. (End)
%t A052278 Table[(4n+3)!/4^n,{n,0,20}] (* _Harvey P. Dale_, Mar 14 2020 *)
%o A052278 (PARI) a(n) = (4*n+3)!/4^n; \\ _Michel Marcus_, Feb 25 2022
%Y A052278 Cf. A052277.
%K A052278 nonn
%O A052278 0,1
%A A052278 _N. J. A. Sloane_, Feb 05 2000