cp's OEIS Frontend

A188245 Number of arrangements of n+2 nonzero numbers x(i) in -5..5 with the sum of x(i)*x(i+1) equal to zero.

%I A188245 #10 Jun 09 2025 20:50:48
%S A188245 100,208,3292,16484,193232,1399640,14715004,123729664,1247614580,
%T A188245 11199296500,110995324320,1029900778912,10129893228408,95800929304216,
%U A188245 939159329686860,8989025842005012,88016972322771816,849227228527469216
%N A188245 Number of arrangements of n+2 nonzero numbers x(i) in -5..5 with the sum of x(i)*x(i+1) equal to zero.
%C A188245 Column 5 of A188249.
%H A188245 R. H. Hardin, <a href="/A188245/b188245.txt">Table of n, a(n) for n = 1..42</a>.
%e A188245 Some solutions for n=4
%e A188245 .-5....1....2...-4....4...-2....2....5....1...-2...-3...-1...-3....4...-1....2
%e A188245 ..4....3....1...-2....3...-4...-5....2....4....5....5...-1....3...-2...-1....1
%e A188245 ..4...-3...-3...-4...-2....2...-5...-1....4...-1....3....1...-1...-5....1....2
%e A188245 ..5...-5...-2....4....3...-2....3....4...-1...-3....4....2...-5....1...-5...-2
%e A188245 .-4....1....5...-4....2....4....4....4....4...-2...-4....1...-1....1...-5....4
%e A188245 .-1...-4....1...-4...-3....3...-3...-5...-3...-3...-1...-4...-2....2....4....2
%K A188245 nonn
%O A188245 1,1
%A A188245 _R. H. Hardin_, Mar 25 2011