A229515 Number of n X 2 0..2 arrays of the median of the corresponding element, the element to the east and the element to the south in a larger (n+1) X 3 0..2 array without adjacent equal elements in the latter.

7, 33, 129, 481, 1751, 6433, 23507, 86295, 316099, 1159635, 4251051, 15590219, 57163723, 209618487, 768636943, 2818506063, 10335115437, 37897559703, 138965833325, 509570185111, 1868532243761, 6851675250519, 25124255606589

Offset

1,1

Comments

Column 2 of A229521.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 8*a(n-2) - 7*a(n-3) - 4*a(n-4) + 19*a(n-5) - 17*a(n-6) + 20*a(n-7) - 12*a(n-8) + 17*a(n-9) + 3*a(n-10) + 13*a(n-11) + 16*a(n-12) - 7*a(n-13) + 2*a(n-14) + 8*a(n-15) -1 3*a(n-16) + 9*a(n-17) - 10*a(n-18) - a(n-19) + a(n-20).

Example

Some solutions for n=3:
  2 0   1 0   2 1   1 2   1 0   1 0   1 1   1 1   1 1   0 1
  0 2   1 1   1 0   1 1   1 2   0 1   1 1   2 0   0 2   1 0
  2 0   1 2   0 1   0 1   2 0   1 2   1 1   1 2   2 0   0 2

Crossrefs

Cf. A229521.

Sequence in context: A350643 A114014 A375549 * A320907 A258458 A320546

Adjacent sequences: A229512 A229513 A229514 * A229516 A229517 A229518

Keyword

nonn

Author

R. H. Hardin, Sep 25 2013

Status

approved