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 A046574 #9 Jul 02 2025 16:01:57 %S A046574 1,4,5,2,19,35,259,483,1815,6864,52195,99671,382109,1469650,5668327, %T A046574 21915550,84913470,329624730,2563431075,4991324415,19463777025, %U A046574 75992317170,297026449005,1162147683450,4551257541090,17839099909800 %N A046574 Distinct numbers in writing first numerator and then denominator of the central elements of the 1/4-Pascal triangle (by row). %e A046574 1/1; 1/1 1/1; 1/1 1/4 1/1; 1/1 5/4 5/4 1/1; 1/1 9/4 5/2 9/4 1/1; 1/1 13/4 19/4 19/4 13/4 1/1; 1/1 17/4 8/1 19/2 8/1 17/4 1/1; 1/1 21/4 49/4 35/2 35/2 49/4 21/4 1/1; ... %Y A046574 Cf. A046563. %K A046574 nonn %O A046574 1,2 %A A046574 _Mohammad K. Azarian_ %E A046574 More terms from _James Sellers_, Dec 14 1999