A209173 Number of nX1 0..3 arrays with every element value z a city block distance of exactly z from another element value z

1, 2, 5, 12, 28, 65, 158, 382, 905, 2145, 5095, 12138, 28738, 68088, 161647, 383228, 908610, 2154138, 5108699, 12115979, 28729086, 68134487, 161588543, 383218255, 908831763, 2155346429, 5111614446, 12122490597, 28749145047, 68180439683

Offset

1,2

Comments

Column 1 of A209178

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -5*a(n-2) +6*a(n-3) -14*a(n-4) +21*a(n-5) -36*a(n-6) +80*a(n-7) -97*a(n-8) +80*a(n-9) -86*a(n-10) +109*a(n-11) -49*a(n-12) -53*a(n-13) +137*a(n-14) -123*a(n-15) +86*a(n-16) -193*a(n-17) +172*a(n-18) -118*a(n-19) -50*a(n-20) +59*a(n-21) -161*a(n-22) +255*a(n-23) -218*a(n-24) +448*a(n-25) -280*a(n-26) +177*a(n-27) -132*a(n-28) +33*a(n-29) -88*a(n-30) +128*a(n-31) -22*a(n-32) -13*a(n-33) +61*a(n-34) -79*a(n-35) +33*a(n-36) -21*a(n-37) +8*a(n-38) -3*a(n-39) +4*a(n-40) -4*a(n-41) +a(n-42) -a(n-43)

Example

Some solutions for n=8
..3....3....2....0....0....0....0....2....3....1....2....0....1....0....0....0
..0....0....2....1....2....2....1....2....1....1....0....3....1....3....1....1
..2....2....2....1....0....0....1....2....1....1....2....0....0....1....1....1
..3....3....2....0....2....2....1....2....3....1....3....0....1....1....3....1
..2....2....2....0....0....2....1....1....0....0....2....3....1....3....1....1
..1....0....1....1....0....2....2....1....0....2....0....2....1....2....1....1
..1....1....1....1....1....2....0....0....1....0....3....0....1....0....3....0
..1....1....1....1....1....2....2....0....1....2....0....2....1....2....0....0

Crossrefs

Sequence in context: A181984 A227807 A206721 * A297496 A302020 A239333

Adjacent sequences: A209170 A209171 A209172 * A209174 A209175 A209176

Keyword

nonn

Author

R. H. Hardin Mar 05 2012

Status

approved