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 A213799 #7 Sep 02 2014 11:18:44 %S A213799 1,8,226,52544,84662388,1012226679296,87098380004205128 %N A213799 Number of n X n 0..7 symmetric arrays with every row summing to floor(n*7/2). %C A213799 Column 7 of A213800. %e A213799 Some solutions for n=4: %e A213799 ..4..4..5..1....7..0..0..7....2..3..7..2....1..1..5..7....5..4..4..1 %e A213799 ..4..6..0..4....0..3..6..5....3..4..0..7....1..2..4..7....4..0..3..7 %e A213799 ..5..0..2..7....0..6..6..2....7..0..5..2....5..4..5..0....4..3..2..5 %e A213799 ..1..4..7..2....7..5..2..0....2..7..2..3....7..7..0..0....1..7..5..1 %Y A213799 Cf. A213800. %K A213799 nonn,more %O A213799 1,2 %A A213799 _R. H. Hardin_, Jun 20 2012