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 A188251 #7 Jul 22 2025 11:05:37 %S A188251 12,120,548,1504,3292,6376,10564,17040,25436,36808,49556,68912,87804, %T A188251 113384,144644,180912,216044,267160,312404,377904,446588,519976, %U A188251 590420,696576,791164,898456,1016756,1159280,1278636,1460936,1598916,1784224 %N A188251 Number of arrangements of 5 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero. %C A188251 Row 3 of A188249 %H A188251 R. H. Hardin, <a href="/A188251/b188251.txt">Table of n, a(n) for n = 1..47</a> %e A188251 Some solutions for n=4 %e A188251 ..3...-2...-2...-3...-1...-1....1....1....4....1...-2...-4....2....2...-1...-3 %e A188251 .-3...-2....3...-4...-1...-3....3...-2....3...-2...-4...-2...-1....1...-1...-2 %e A188251 ..2....3...-1....3....3....2....4...-4...-4...-1....2....1....2...-2....4....2 %e A188251 ..3....1...-3...-2....2....1...-3....3...-2...-3...-4....3...-4...-4....3....2 %e A188251 ..3...-1...-2...-3...-2....1....1....2....4....1...-2...-3...-3....2...-3...-3 %K A188251 nonn %O A188251 1,1 %A A188251 _R. H. Hardin_ Mar 25 2011