cp's OEIS Frontend

A188244 Number of arrangements of n+2 nonzero numbers x(i) in -4..4 with the sum of x(i)*x(i+1) equal to zero.

%I A188244 #7 Jul 22 2025 11:04:55
%S A188244 64,144,1504,7092,58824,368588,2880240,20265640,156028036,1154193268,
%T A188244 8877588920,67251222980,518783061524,3979996140580,30813430250120,
%U A188244 238176520092556,1850203922639624,14371954026347848,111969329295785092
%N A188244 Number of arrangements of n+2 nonzero numbers x(i) in -4..4 with the sum of x(i)*x(i+1) equal to zero.
%C A188244 Column 4 of A188249
%H A188244 R. H. Hardin, <a href="/A188244/b188244.txt">Table of n, a(n) for n = 1..59</a>
%e A188244 Some solutions for n=5
%e A188244 ..4...-4....2....4...-4....1....3....1....3...-3....2....4...-2....1...-1...-4
%e A188244 .-1....3...-1....3....1....4....2...-1...-2...-3....2....1...-2...-3....3....4
%e A188244 .-3....4...-2...-4...-3...-3....4....4...-1...-3....3...-1...-1...-1...-3....4
%e A188244 ..3...-2...-3...-4...-2...-1...-2...-1....4....2...-2...-1...-1....4...-3...-4
%e A188244 ..4...-4....2...-1...-4....1....3...-1....1...-2....2....4....1....1...-1...-3
%e A188244 .-1....4....4....4....1....3...-3...-2...-4....2....2....2...-2...-4...-2...-2
%e A188244 .-2....4...-2...-4...-3....1...-3...-3...-2...-2...-2...-4....2...-1....1....1
%K A188244 nonn
%O A188244 1,1
%A A188244 _R. H. Hardin_ Mar 25 2011