cp's OEIS Frontend

A188255 Number of arrangements of 9 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero.

%I A188255 #6 Jul 22 2025 11:06:06
%S A188255 140,16272,355396,2880240,14715004,55994544,168083116,445304272,
%T A188255 1033172284,2215496776,4323822892
%N A188255 Number of arrangements of 9 nonzero numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero.
%C A188255 Row 7 of A188249
%e A188255 Some solutions for n=4
%e A188255 .-4...-2...-3...-4...-3...-3...-4...-3...-4...-3...-3...-3...-2...-2...-4...-4
%e A188255 .-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4...-4
%e A188255 .-2....1....3....1....1....1....1....1....1...-3....4....2...-4...-3...-2....3
%e A188255 .-1....1...-4....2...-1....3...-4...-1...-2....2....1....2...-4...-4....3....4
%e A188255 .-4...-3...-3...-1...-1...-1....4....3...-1...-2....3...-1....3....2...-1...-1
%e A188255 ..3....4...-3....3...-2....4....2...-4....1....1...-2...-3...-1...-3...-2....4
%e A188255 .-1....3....1...-2....3...-1....3...-2....3...-4...-1....2....4....4....4....2
%e A188255 ..3....2....2....3...-1...-4...-3....1...-2....4....1...-3...-3...-1...-3...-4
%e A188255 .-4...-4...-4....1....1....1...-1....2....4....2....2...-1....3....2...-1....2
%K A188255 nonn
%O A188255 1,1
%A A188255 _R. H. Hardin_ Mar 25 2011