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 A276637 #4 Sep 08 2016 08:32:09 %S A276637 1,16,936,87336,9929000,1267945800,174470351760,25288627665840, %T A276637 3812023555600680,591698219294831040,94094630284245419136, %U A276637 15245574601442117896656,2511237778001138580615056,419023242828557373939828896,70761397145460782667032755200 %N A276637 Number of up-down sequences with n copies each of 1,2,...,5. %e A276637 a(1) = 16: 13254, 14253, 14352, 15243, 15342, 23154, 24153, 24351, 25143, 25341, 34152, 34251, 35142, 35241, 45132, 45231. %e A276637 a(2) = 936: 1213243545, 1213254534, 1214243535, 1214253435, ..., 4545121323, 4545132312, 4545231213, 4545231312. %Y A276637 Row n=5 of A275784. %K A276637 nonn %O A276637 0,2 %A A276637 _Alois P. Heinz_, Sep 08 2016