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 A200552 #7 Apr 18 2023 09:27:36 %S A200552 154,2134,27806,372150,5012084,68263780,936121220,12911643944, %T A200552 178893425570,2488110363432,34717386812304,485767803378730, %U A200552 6813227225653584,95761068651953630,1348433104134460586 %N A200552 Number of -7..7 arrays x(0..n+1) of n+2 elements with zero sum and nonzero second differences. %C A200552 Column 7 of A200553. %H A200552 R. H. Hardin, <a href="/A200552/b200552.txt">Table of n, a(n) for n = 1..83</a> %e A200552 Some solutions for n=3 %e A200552 .-6....1...-7....5....0...-6....4....1....1....0....1...-4....7...-6...-3....2 %e A200552 ..2...-3....5...-4....2....5...-6...-2....3...-1....2....0...-1....6...-4....0 %e A200552 ..1...-2....2...-1...-4....4...-2....5....1....5....1....3....4...-1...-2....3 %e A200552 ..2....1...-3....5...-4....2....4...-3....2...-2...-5....2...-3....1....5...-5 %e A200552 ..1....3....3...-5....6...-5....0...-1...-7...-2....1...-1...-7....0....4....0 %Y A200552 Cf. A200553. %K A200552 nonn %O A200552 1,1 %A A200552 _R. H. Hardin_, Nov 19 2011