A207427 Number of 3Xn 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 0 1 0 vertically

6, 36, 114, 361, 1425, 5625, 20550, 75076, 282494, 1062961, 3953885, 14707225, 54963220, 205406224, 766145724, 2857650849, 10667504721, 39821399809, 148599935192, 554524472896, 2069606677336, 7724225004001, 28826640215153

Offset

1,1

Comments

Row 3 of A207426

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -3*a(n-2) +16*a(n-3) +35*a(n-4) -53*a(n-5) +54*a(n-6) -183*a(n-7) -315*a(n-8) +430*a(n-9) -115*a(n-10) +307*a(n-11) +592*a(n-12) -693*a(n-13) +261*a(n-14) -288*a(n-15) -285*a(n-16) +315*a(n-17) -202*a(n-18) +153*a(n-19) -27*a(n-20) -2*a(n-21) +5*a(n-22) -5*a(n-23) +a(n-24)

Example

Some solutions for n=4
..1..0..0..1....1..1..1..1....0..0..1..1....1..1..1..0....0..1..1..1
..1..0..1..1....1..1..1..1....0..0..1..1....1..0..0..1....1..0..0..1
..0..0..1..1....1..1..1..1....0..0..1..1....0..1..1..1....1..1..0..0

Crossrefs

Sequence in context: A172137 A061804 A207421 * A207712 A207718 A262467

Adjacent sequences: A207424 A207425 A207426 * A207428 A207429 A207430

Keyword

nonn

Author

R. H. Hardin Feb 17 2012

Status

approved