A209360 Number of nX1 1..3 arrays with every element value z a city block distance of exactly z from another element value z

0, 1, 1, 3, 2, 8, 10, 21, 35, 61, 104, 186, 318, 554, 964, 1679, 2904, 5049, 8766, 15231, 26462, 45992, 79958, 139000, 241606, 419980, 729994, 1268847, 2205303, 3832967, 6661973, 11578805, 20124641, 34977856, 60794002, 105664602, 183653069

Offset

1,4

Comments

Column 1 of A209365

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -3*a(n-2) +3*a(n-3) -5*a(n-4) +5*a(n-5) -5*a(n-6) +9*a(n-7) -8*a(n-8) +2*a(n-9) +a(n-10) -4*a(n-11) +16*a(n-12) -22*a(n-13) +18*a(n-14) -16*a(n-15) +13*a(n-16) -8*a(n-17) -4*a(n-18) +2*a(n-19) -5*a(n-20) +9*a(n-21) -7*a(n-22) +6*a(n-23) -4*a(n-24) +4*a(n-25) -a(n-26) -a(n-27) -a(n-28)

Example

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

Crossrefs

Sequence in context: A363816 A060921 A163356 * A095013 A094188 A088551

Adjacent sequences: A209357 A209358 A209359 * A209361 A209362 A209363

Keyword

nonn

Author

R. H. Hardin Mar 06 2012

Status

approved