A229640 Number of defective 3-colorings of a 4 X n 0..2 array connected horizontally, diagonally and antidiagonally with exactly two mistakes, and colors introduced in row-major 0..2 order.

0, 202, 1496, 10227, 77620, 535671, 3723370, 25022190, 166505166, 1090285513, 7066637900, 45333775056, 288422981684, 1821192582307, 11424271291526, 71241698297248, 441922120307156, 2728236364222397, 16770150954151850

Offset

1,2

Comments

Row 4 of A229637.

Links

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

Formula

Empirical: a(n) = 9*a(n-1) + 21*a(n-2) - 270*a(n-3) - 357*a(n-4) + 2967*a(n-5) + 4906*a(n-6) - 10083*a(n-7) - 18957*a(n-8) + 15750*a(n-9) + 31293*a(n-10) - 13335*a(n-11) - 23929*a(n-12) + 6426*a(n-13) + 7824*a(n-14) - 1336*a(n-15) - 1152*a(n-16) + 96*a(n-17) + 64*a(n-18) for n > 21.

Example

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

Crossrefs

Sequence in context: A260280 A252993 A252987 * A221892 A332120 A064100

Adjacent sequences: A229637 A229638 A229639 * A229641 A229642 A229643

Keyword

nonn

Author

R. H. Hardin, Sep 27 2013

Status

approved