A218517 Number of n X 3 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..3 n X 3 array.
16, 286, 4634, 76214, 1254462, 20655650, 340133516, 5601018048, 92232936766, 1518816980614, 25010647012824, 411855079591306, 6782095959978908, 111682064830460636, 1839089815861812230, 30284641999299892776
Offset: 1
Keywords
Examples
Some solutions for n=3: ..0..0..1....2..0..3....3..2..2....2..2..3....0..0..0....0..0..1....1..1..1 ..0..0..0....0..0..1....2..1..1....2..2..0....2..0..1....3..1..1....2..1..2 ..1..0..1....2..0..0....2..1..3....0..0..0....3..0..0....1..1..3....1..1..2
Links
- R. H. Hardin, Table of n, a(n) for n = 1..157
Crossrefs
Cf. A218522.
Formula
Empirical: a(n) = 18*a(n-1) - 19*a(n-2) - 96*a(n-3) - 112*a(n-4) - a(n-5) + 140*a(n-6) + 64*a(n-7).
Empirical g.f.: 2*x*(8 - x - 105*x^2 - 114*x^3 - 48*x^4 + 156*x^5 + 96*x^6) / (1 - 18*x + 19*x^2 + 96*x^3 + 112*x^4 + x^5 - 140*x^6 - 64*x^7). - Colin Barker, Jul 24 2018
Comments