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 A200452 #7 Jul 22 2025 15:49:55 %S A200452 102,1148,12002,127988,1375006,14923636,163058296,1791564880, %T A200452 19771609900,219008350922,2433568582846,27114470656254, %U A200452 302815705130546,3388823734521446,37993433832232370,426648365048068166 %N A200452 Number of -6..6 arrays x(0..n+1) of n+2 elements with zero sum and nonzero first and second differences. %C A200452 Column 6 of A200454 %H A200452 R. H. Hardin, <a href="/A200452/b200452.txt">Table of n, a(n) for n = 1..119</a> %e A200452 Some solutions for n=3 %e A200452 ..2....0...-3....0....3....6...-3...-6....6....3...-3....2....3...-1....2...-1 %e A200452 ..5...-5....1...-5...-2...-5....6....2....1....5...-1....3...-3....6....3...-2 %e A200452 .-5....0....6...-2....4....2...-5...-2...-5....2...-2....1...-5...-3...-4...-5 %e A200452 .-6....1....0....4...-1...-1....6....4....4...-6....0...-5...-1....2....0....5 %e A200452 ..4....4...-4....3...-4...-2...-4....2...-6...-4....6...-1....6...-4...-1....3 %K A200452 nonn %O A200452 1,1 %A A200452 _R. H. Hardin_ Nov 18 2011