A211689 Number of -4..4 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 two or three distinct values for every i<=n and j<=n

80, 216, 498, 1064, 2200, 4448, 8844, 17552, 34384, 67836, 132308, 260904, 509178, 1006144, 1969566, 3904484, 7675178, 15271538, 30158642, 60234204, 119509036, 239563440, 477465048, 960417468, 1922353398, 3879214910, 7795367130

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +16*a(n-2) -80*a(n-3) -93*a(n-4) +694*a(n-5) +149*a(n-6) -3418*a(n-7) +910*a(n-8) +10491*a(n-9) -5972*a(n-10) -20678*a(n-11) +16520*a(n-12) +25848*a(n-13) -26344*a(n-14) -19141*a(n-15) +25313*a(n-16) +6692*a(n-17) -14094*a(n-18) +234*a(n-19) +4010*a(n-20) -760*a(n-21) -420*a(n-22) +120*a(n-23)

Example

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

Crossrefs

Sequence in context: A044412 A044793 A359517 * A364719 A202439 A203355

Adjacent sequences: A211686 A211687 A211688 * A211690 A211691 A211692

Keyword

nonn

Author

R. H. Hardin Apr 18 2012

Status

approved