A217451 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal and vertical neighbors in a random 0..2 n X 2 array.
3, 15, 69, 253, 1049, 4205, 16887, 68015, 273471, 1100135, 4425449, 17801365, 71607677, 288046417, 1158686263, 4660895899, 18748771139, 75418217399, 303374944277, 1220346484777, 4908927310389, 19746496259789, 79431633434755
Offset: 1
Keywords
Examples
Some solutions for n=3: ..2..2....0..0....0..0....0..0....1..0....2..2....0..0....1..2....0..0....1..0 ..2..1....0..0....0..0....1..0....0..0....0..1....1..0....1..1....2..0....0..0 ..1..1....2..1....2..2....0..0....2..0....0..0....2..2....1..2....0..0....1..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..128
Crossrefs
Cf. A217457.
Formula
Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + 6*a(n-3) - 5*a(n-4) + a(n-5) - 17*a(n-6) - 14*a(n-7) - 26*a(n-8) - 4*a(n-9).
Empirical g.f.: x*(3 + 6*x + 15*x^2 - 17*x^3 + 8*x^4 - 43*x^5 - 12*x^6 - 62*x^7 - 12*x^8) / (1 - 3*x - 3*x^2 - 6*x^3 + 5*x^4 - x^5 + 17*x^6 + 14*x^7 + 26*x^8 + 4*x^9). - Colin Barker, Mar 09 2018
Comments