cp's OEIS Frontend

A188247 Number of arrangements of n+2 nonzero numbers x(i) in -7..7 with the sum of x(i)*x(i+1) equal to zero.

%I A188247 #6 Jul 22 2025 11:05:09
%S A188247 196,532,10564,75080,1142180,11953848,168083116,2026547348,
%T A188247 27843005992,355600251460,4851985495460,63719148177636,
%U A188247 867980001700376,11577646834184824,157763834094118596
%N A188247 Number of arrangements of n+2 nonzero numbers x(i) in -7..7 with the sum of x(i)*x(i+1) equal to zero.
%C A188247 Column 7 of A188249
%e A188247 Some solutions for n=4
%e A188247 .-3...-1...-3....2....4...-6....5....3...-4....2...-1....4...-6...-6....3...-6
%e A188247 .-7...-7...-1...-1...-1...-1...-1....6...-5...-5....1....3...-6....3...-1...-4
%e A188247 ..1....2...-6...-2....2...-6....1...-1....3....6...-2...-6....3....2...-2....3
%e A188247 ..4....6...-2....3....5....1....4...-6...-3....2....2...-5...-6....6....4...-2
%e A188247 .-2....5....3....3....2....2...-2....2....2....7....7....3...-7....1....3...-6
%e A188247 ..5...-7...-5...-1...-7...-4...-5...-3....5....2...-1...-3....6...-6...-1....3
%K A188247 nonn
%O A188247 1,1
%A A188247 _R. H. Hardin_ Mar 25 2011