A211501 Number of -3..3 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having one, two or three distinct values for every i<=n and j<=n.

49, 143, 357, 879, 2053, 4805, 10971, 25233, 57391, 131643, 300783, 692847, 1595765, 3701759, 8601369, 20105533, 47103881, 110883033, 261621763, 619556193, 1470188991, 3498411151, 8338717447, 19916838255, 47634215409, 114096061487

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 6*a(n-1) +6*a(n-2) -97*a(n-3) +62*a(n-4) +668*a(n-5) -852*a(n-6) -2556*a(n-7) +4359*a(n-8) +5935*a(n-9) -12593*a(n-10) -8545*a(n-11) +22727*a(n-12) +7400*a(n-13) -26431*a(n-14) -3396*a(n-15) +19783*a(n-16) +389*a(n-17) -9298*a(n-18) +302*a(n-19) +2606*a(n-20) -118*a(n-21) -392*a(n-22) +12*a(n-23) +24*a(n-24).

Example

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

Crossrefs

Sequence in context: A020256 A304171 A118160 * A345115 A009404 A316121

Adjacent sequences: A211498 A211499 A211500 * A211502 A211503 A211504

Keyword

nonn

Author

R. H. Hardin, Apr 13 2012

Status

approved