A199914 Number of -n..n arrays x(0..6) of 7 elements with zero sum, and adjacent elements not equal modulo three (with -1 modulo 3 = 2)

56, 654, 5206, 24864, 77874, 216530, 518560, 1071202, 2114394, 3876376, 6593960, 10975656, 17458840, 26545266, 39896954, 58112992, 82129122, 115325122, 158200672, 212380574, 284094678, 373133880, 482198944, 621972384, 790417208

Offset

1,1

Comments

Row 7 of A199909

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = a(n-1) +6*a(n-3) -6*a(n-4) -15*a(n-6) +15*a(n-7) +20*a(n-9) -20*a(n-10) -15*a(n-12) +15*a(n-13) +6*a(n-15) -6*a(n-16) -a(n-18) +a(n-19)

Example

Some solutions for n=6
.-5...-3...-3....3...-6....3...-6....3....0...-3....4...-6....4...-5...-6...-3
.-3...-1....5....1...-5...-2....2...-5....5....4...-4....5...-3...-3...-1...-1
..2...-5....4....0....6...-4...-5....2...-3...-4...-6...-5....2....2....6....0
..3....2...-3....1....2....3....5...-3....4....6...-1....6....3....3....1...-2
..4....6....1....0....0....2....3....1...-1...-1....6...-1....4....1....6....5
.-1...-5...-6....1....5...-5....1....5...-6....4....4...-5...-6....3...-5....4
..0....6....2...-6...-2....3....0...-3....1...-6...-3....6...-4...-1...-1...-3

Crossrefs

Sequence in context: A219475 A264212 A027813 * A190535 A190604 A136006

Adjacent sequences: A199911 A199912 A199913 * A199915 A199916 A199917

Keyword

nonn

Author

R. H. Hardin Nov 11 2011

Status

approved