A222890 Number of n X 1 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.

1, 2, 3, 7, 20, 67, 255, 1080, 5016, 25249, 136289, 780658, 4696002, 29374011, 189373083, 1248978556, 8376922028, 56874440053, 389553674037, 2685020105574, 18589701176694, 129115803986575, 898809701733551, 6266899328414512

Offset

1,2

Comments

Column 1 of A222894.

Links

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

Formula

Empirical: a(n) = 22*a(n-1) - 190*a(n-2) + 820*a(n-3) - 1849*a(n-4) + 2038*a(n-5) - 840*a(n-6) for n>8.

Empirical g.f.: x*(1 + x)*(1 - 21*x + 170*x^2 - 669*x^3 + 1314*x^4 - 1157*x^5 + 309*x^6) / ((1 - x)*(1 - 2*x)*(1 - 3*x)*(1 - 4*x)*(1 - 5*x)*(1 - 7*x)). - Colin Barker, Aug 16 2018

Example

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

Crossrefs

Cf. A222894.

Sequence in context: A222939 A222867 A222776 * A011968 A080021 A306666

Adjacent sequences: A222887 A222888 A222889 * A222891 A222892 A222893

Keyword

nonn

Author

R. H. Hardin, Mar 08 2013

Status

approved