A198281 Number of 2nX8 0..2 arrays with values 0..2 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors

4, 52, 662, 8784, 112750, 1478756, 19399132, 254611868, 3341562350, 43867978456, 575917076750, 7560973295748, 99265283146820, 1303224636522612, 17109671915393798, 224628189063611744, 2949082376664452782

Offset

1,1

Comments

Column 4 of A198285

Links

R. H. Hardin, Table of n, a(n) for n = 1..193

Formula

Empirical: a(n) = 20*a(n-1) -94*a(n-2) +30*a(n-3) +991*a(n-4) -14152*a(n-5) +57737*a(n-6) +47122*a(n-7) -441218*a(n-8) +2956618*a(n-9) -10811467*a(n-10) -23072476*a(n-11) +84378808*a(n-12) -161949862*a(n-13) +516000620*a(n-14) +2832666716*a(n-15) -3992016864*a(n-16) -5147127328*a(n-17) +8009660032*a(n-18) -125833211136*a(n-19) -133111885824*a(n-20) +321245103104*a(n-21) -748696293376*a(n-22) +5854699044864*a(n-23) +11597031440384*a(n-24) -9315056222208*a(n-25) +725672263680*a(n-26) -167805362634752*a(n-27) -267408019292160*a(n-28) +267698466455552*a(n-29) +891968070615040*a(n-30) +545959062798336*a(n-31) +2070380395102208*a(n-32) +1440360232386560*a(n-33) -14953358137753600*a(n-34) -4644337115725824*a(n-35) +18014398509481984*a(n-36)

Example

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

Crossrefs

Sequence in context: A221727 A144339 A155661 * A220933 A222321 A222138

Adjacent sequences: A198278 A198279 A198280 * A198282 A198283 A198284

Keyword

nonn

Author

R. H. Hardin Oct 23 2011

Status

approved