A188184 Number of strictly increasing arrangements of 6 numbers in -(n+4)..(n+4) with sum zero.
32, 94, 227, 480, 920, 1636, 2739, 4370, 6698, 9926, 14293, 20076, 27594, 37212, 49341, 64444, 83036, 105690, 133037, 165772, 204654, 250510, 304239, 366814, 439284, 522780, 618513, 727782, 851974, 992568, 1151137, 1329352, 1528984
Offset: 1
Keywords
Examples
Some solutions for n=5 .-7...-9...-6...-4...-8...-7...-7...-6...-7...-6...-8...-9...-6...-6...-9...-8 .-5...-5...-4...-2...-6...-5...-2...-5...-3...-3...-3...-2...-3...-5...-6...-3 .-4....1...-1...-1....1...-4...-1...-2....0...-2...-2....0...-2...-4....1...-1 ..2....3....2....1....2....1....0....0....1...-1...-1....2....1....0....3....1 ..5....4....4....2....3....7....3....6....3....5....5....4....3....7....4....3 ..9....6....5....4....8....8....7....7....6....7....9....5....7....8....7....8
Links
- R. H. Hardin, Table of n, a(n) for n = 1..200
Formula
Empirical: a(n)=3*a(n-1)-2*a(n-2)-a(n-3)+2*a(n-5)-a(n-6)-a(n-7)+2*a(n-8)-a(n-10)-2*a(n-11)+3*a(n-12)-a(n-13).
Empirical: G.f. -x*(-32 +2*x -9*x^2 -19*x^3 -28*x^4 +x^5 +5*x^6 -17*x^7 +x^8 +10*x^9 +13*x^10 -23*x^11 +8*x^12) / ( (1+x) *(1+x+x^2) *(x^4+x^3+x^2+x+1) *(x-1)^6 ). - R. J. Mathar, Mar 26 2011
Comments