A281057 Number of 2 X n 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.

0, 1, 6, 34, 104, 251, 535, 1076, 2090, 3956, 7353, 13474, 24417, 43846, 78142, 138374, 243687, 427098, 745403, 1296072, 2246018, 3880504, 6686165, 11491746, 19706373, 33722458, 57596214, 98195818, 167136611, 284039674, 482013727, 816869276

Offset

1,3

Links

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

Formula

Empirical: a(n) = 5*a(n-1) - 7*a(n-2) - 2*a(n-3) + 10*a(n-4) - 2*a(n-5) - 5*a(n-6) + a(n-7) + a(n-8) for n>14.

Empirical g.f.: x^2*(1 + x + 11*x^2 - 22*x^3 - 29*x^4 + 18*x^5 + 43*x^6 + 14*x^7 - 31*x^8 - 13*x^9 + 8*x^10 + 2*x^11 - x^12) / ((1 - x)^2*(1 - x - x^2)^3). - Colin Barker, Feb 15 2019

Example

Some solutions for n=4:
..0..0..0..1. .0..1..1..1. .0..1..1..0. .0..0..1..1. .0..1..0..0
..0..1..1..0. .0..0..1..0. .0..0..0..0. .1..1..0..1. .0..0..1..0

Crossrefs

Row 2 of A281056.

Sequence in context: A319199 A305164 A067389 * A341290 A061616 A368757

Adjacent sequences: A281054 A281055 A281056 * A281058 A281059 A281060

Keyword

nonn

Author

R. H. Hardin, Jan 13 2017

Status

approved