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 A201806 #8 Oct 14 2024 15:31:59 %S A201806 1,7,19,151,631,4621,23857,164599,948871,6359617,38944357,258107389, %T A201806 1636264813,10819063087,70033892299,463844386999,3042796871863, %U A201806 20218887555601,133836585431269,892623030133681,5947033694372881 %N A201806 Number of arrays of n integers in -3..3 with sum zero and equal numbers of elements greater than zero and less than zero. %H A201806 R. H. Hardin, <a href="/A201806/b201806.txt">Table of n, a(n) for n = 1..210</a> %e A201806 Some solutions for n=7: %e A201806 .-3....2....0...-1...-3....3....1....3...-1....3....0...-2....1...-3....0...-3 %e A201806 .-3....3...-2...-1....1....1...-1....2...-3....3....1....3....3...-2....0....3 %e A201806 .-3....0....3...-2...-1....0...-2...-2....1....1...-2...-3....0....1....2....0 %e A201806 ..3...-3...-2....2...-1...-1....3...-2....2...-2....2....3....2....0...-3....0 %e A201806 ..3....2....3....1....3....1....0....0....0...-2...-2....2...-1....3...-2....0 %e A201806 ..3...-3....1....0....1...-1....1....2...-1...-3....3...-3...-3....2....0...-3 %e A201806 ..0...-1...-3....1....0...-3...-2...-3....2....0...-2....0...-2...-1....3....3 %Y A201806 Column 3 of A201811. %K A201806 nonn %O A201806 1,2 %A A201806 _R. H. Hardin_, Dec 05 2011