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 A200189 #7 Jul 22 2025 15:43:46 %S A200189 1,10,44,242,1298,7266,40632,231916,1320876,7630236,43951298, %T A200189 255926506,1485664226,8700154180,50792100530,298703878402, %U A200189 1751415860436,10333766393384,60797757383394,359661008763242,2121869963574120 %N A200189 Number of -5..5 arrays x(0..n-1) of n elements with zero sum, adjacent elements differing by more than one, and elements alternately increasing and decreasing. %C A200189 Column 5 of A200192 %H A200189 R. H. Hardin, <a href="/A200189/b200189.txt">Table of n, a(n) for n = 1..200</a> %e A200189 Some solutions for n=5 %e A200189 .-1...-3....4....2....1...-4...-5...-1...-1...-1....2....2...-3....0....2...-3 %e A200189 ..2....5...-4....4...-4....3....2...-5....5....4...-4....4....5....4....5....5 %e A200189 .-4...-2....1...-3....5...-3...-3....3...-4...-1....2...-5...-3...-3...-5...-1 %e A200189 ..4....1...-2....0...-2....5....4...-1....1....1...-3....1....2....1....0....2 %e A200189 .-1...-1....1...-3....0...-1....2....4...-1...-3....3...-2...-1...-2...-2...-3 %K A200189 nonn %O A200189 1,2 %A A200189 _R. H. Hardin_ Nov 14 2011