A232258 Number of (1+1)X(n+1) 0..2 arrays with every element both >= and <= some horizontal or antidiagonal neighbor

9, 37, 215, 1287, 7673, 45709, 272417, 1623601, 9676571, 57671897, 343721665, 2048564473, 12209345763, 72767112987, 433688490081, 2584762523789, 15405060215819, 91813417313133, 547203547448227, 3261306801365497

Offset

1,1

Comments

Row 1 of A232257

Links

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

Formula

Empirical: a(n) = 6*a(n-1) -3*a(n-2) +19*a(n-3) -16*a(n-4) +13*a(n-5) -45*a(n-6) -10*a(n-7) -26*a(n-8) -11*a(n-9) +26*a(n-10) +4*a(n-11) -4*a(n-12) for n>13.

Empirical g.f.: 9*x -x^2*(-37 +7*x -108*x^2 +107*x^3 -39*x^4 +312*x^5 +99*x^6 +173*x^7 +27*x^8 -184*x^9 -20*x^10 +28*x^11)/(x^3 -2*x^2 +x -1)/(4*x^9 +4*x^8 -22*x^7 -33*x^6 -14*x^5 -7*x^4 +12*x^3 +4*x^2 +5*x -1) . - R. J. Mathar, Nov 09 2018

Example

Some solutions for n=7
..0..0..1..1..1..2..0..0....0..0..1..1..0..2..0..0....0..0..1..1..2..2..1..1
..0..0..1..2..2..1..0..0....2..2..1..0..2..0..2..2....2..2..2..2..0..0..2..2

Crossrefs

Sequence in context: A183327 A364700 A199894 * A370244 A370269 A026686

Adjacent sequences: A232255 A232256 A232257 * A232259 A232260 A232261

Keyword

nonn

Author

R. H. Hardin, Nov 21 2013

Status

approved