A165379 Number of slanted nX6 (i=1..n)X(j=i..6+i-1) 1..4 arrays with all 1s connected, all 2s connected, all 3s connected, all 4s connected, 1 in the upper left corner, 2 in the upper right corner, 3 in the lower left corner, 4 in the lower right corner, and with no element having more than 2 neighbors with the same value

101, 233, 265, 335, 409, 483, 557, 631, 705, 779, 853, 927, 1001, 1075, 1149, 1223

Offset

2,1

Links

Table of n, a(n) for n=2..17.

Formula

Empirical: a(n)=2*a(n-1)-a(n-2) for n>=7

Example

Some solutions for n=3
...1.1.1.1.2.2.......1.1.2.2.2.2.......1.1.1.1.1.2.......1.1.1.2.2.2....
.....3.3.1.2.4.4.......3.3.4.4.2.2.......3.3.4.1.2.2.......3.3.2.4.2.2..
.......3.3.3.3.4.4.......3.3.4.4.4.4.......3.4.4.4.4.4.......3.2.4.4.4.4
------
...1.1.2.2.2.2.......1.1.1.2.2.2.......1.1.4.4.4.2.......1.2.2.2.2.2....
.....1.1.1.4.2.2.......2.2.2.4.4.4.......1.1.1.4.4.4.......2.4.4.4.4.4..
.......3.3.4.4.4.4.......3.3.3.3.4.4.......3.3.3.3.4.4.......3.3.3.3.4.4

Crossrefs

Sequence in context: A142838 A142910 A259739 * A127348 A061191 A085610

Adjacent sequences: A165376 A165377 A165378 * A165380 A165381 A165382

Keyword

nonn

Author

R. H. Hardin Sep 17 2009

Status

approved