A222550 Number of (n+3) X 1 arrays of occupancy after each element moves up to +-3 places but not 0.

31, 102, 359, 1279, 4537, 15929, 56041, 197313, 694561, 2443809, 8598567, 30254246, 106446779, 374510087, 1317616614, 4635657529, 16309130459, 57378359687, 201866467555, 710197956209, 2498584711494, 8790394014302, 30925899907467

Offset

1,1

Comments

Column 3 of A222555.

Links

R. H. Hardin, Table of n, a(n) for n = 1..131

Formula

Empirical: a(n) = 7*a(n-1) -15*a(n-2) +10*a(n-3) +4*a(n-4) -36*a(n-5) +73*a(n-6) -29*a(n-7) -21*a(n-8) -a(n-9).

Empirical g.f.: x*(31 - 115*x + 110*x^2 - 14*x^3 - 175*x^4 + 473*x^5 - 224*x^6 - 148*x^7 - 7*x^8) / (1 - 7*x + 15*x^2 - 10*x^3 - 4*x^4 + 36*x^5 - 73*x^6 + 29*x^7 + 21*x^8 + x^9). - Colin Barker, Aug 16 2018

Example

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

Crossrefs

Cf. A222555.

Sequence in context: A323617 A142096 A268986 * A075936 A221902 A289134

Adjacent sequences: A222547 A222548 A222549 * A222551 A222552 A222553

Keyword

nonn

Author

R. H. Hardin, Feb 24 2013

Status

approved