A198248 Number of 2nX6 0..4 arrays with values 0..4 introduced in row major order and each element equal to exactly two horizontal and vertical neighbors

2, 40, 1675, 81440, 4059950, 203087097, 10164141586, 508740409496, 25464106707391, 1274565023173456, 63796351813851410, 3193226785065121249, 159831987739494226958, 8000141016276333546184, 400434589880788614683443

Offset

1,1

Comments

Column 3 of A198253

Links

R. H. Hardin, Table of n, a(n) for n = 1..196

Formula

Empirical: a(n) = 72*a(n-1) -1224*a(n-2) +6597*a(n-3) -19006*a(n-4) +172500*a(n-5) -532320*a(n-6) -1349230*a(n-7) -4127885*a(n-8) +33277832*a(n-9) +64772160*a(n-10) -69056031*a(n-11) -640524524*a(n-12) -747043292*a(n-13) +1639831968*a(n-14) +4384055040*a(n-15) +3468395008*a(n-16) -6524486656*a(n-17) -12366217216*a(n-18) -2784755712*a(n-19) +4957667328*a(n-20) +8589934592*a(n-21)

Example

Some solutions for n=4
..0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..1..1
..0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..1..2..2....0..0..1..2..2..1
..2..2..3..3..0..0....3..3..2..2..4..4....1..1..3..3..4..4....1..1..1..2..2..1
..2..2..3..3..0..0....3..3..2..2..4..4....1..1..3..3..4..4....1..0..0..1..1..1
..4..4..4..4..4..4....2..2..1..1..0..0....4..4..4..4..2..2....1..0..0..1..0..0
..4..1..1..3..3..4....2..2..1..1..0..0....4..0..0..4..2..2....1..1..1..1..0..0
..4..1..1..3..3..4....4..4..2..2..1..1....4..0..0..4..0..0....3..3..0..0..3..3
..4..4..4..4..4..4....4..4..2..2..1..1....4..4..4..4..0..0....3..3..0..0..3..3

Crossrefs

Sequence in context: A286124 A275931 A099707 * A261732 A292418 A163826

Adjacent sequences: A198245 A198246 A198247 * A198249 A198250 A198251

Keyword

nonn

Author

R. H. Hardin Oct 22 2011

Status

approved