A231082 Number of 3Xn 0..2 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 3 and at least one element with value (x(i,j)-1) mod 3, and upper left element zero

0, 2, 50, 136, 2820, 38000, 421920, 6118120, 80521240, 1094128296, 15096212664, 206478042568, 2844940947752, 39196681965960, 540088040101912, 7448443982546312, 102716411297423656, 1416714539550709832

Offset

1,2

Comments

Row 3 of A231080

Links

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

Formula

Empirical: a(n) = 16*a(n-1) -22*a(n-2) +202*a(n-3) -4786*a(n-4) +10954*a(n-5) -108876*a(n-6) +494726*a(n-7) -867601*a(n-8) +5712046*a(n-9) -8074486*a(n-10) +12131984*a(n-11) -53462460*a(n-12) -197644232*a(n-13) -17742728*a(n-14) -134970336*a(n-15) +1087452416*a(n-16) +2848787264*a(n-17) -3062176448*a(n-18) +24945118592*a(n-19) -26105584256*a(n-20) -10840879872*a(n-21) -37458373632*a(n-22) +16021963776*a(n-23) +13901665280*a(n-24) +34409371648*a(n-25) +2558844928*a(n-26) -74692345856*a(n-27) +18690605056*a(n-28) +56174247936*a(n-29) +5405671424*a(n-30) -17857249280*a(n-31) -23081254912*a(n-32) +14482931712*a(n-33) -486539264*a(n-34) -268435456*a(n-35)

Example

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

Crossrefs

Sequence in context: A050800 A231051 A317819 * A318426 A265962 A318094

Adjacent sequences: A231079 A231080 A231081 * A231083 A231084 A231085

Keyword

nonn

Author

R. H. Hardin, Nov 03 2013

Status

approved