A203383 Number of nX2 0..6 arrays with every nonzero element less than or equal to at least two horizontal and vertical neighbors

1, 7, 49, 252, 1519, 11585, 86156, 606221, 4325033, 31601858, 230910283, 1678821743, 12222650420, 89226320509, 651653318187, 4758063707123, 34749854417031, 253886944760666, 1855215535222434, 13557207303083137

Offset

1,2

Comments

Column 2 of A203389

Links

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

Formula

Empirical: a(n) = 28*a(n-1) -357*a(n-2) +2947*a(n-3) -18592*a(n-4) +94955*a(n-5) -401184*a(n-6) +1451988*a(n-7) -4590176*a(n-8) +12768384*a(n-9) -31951051*a(n-10) +72039820*a(n-11) -147425146*a(n-12) +278988578*a(n-13) -478122096*a(n-14) +772651010*a(n-15) -1140165206*a(n-16) +1561997938*a(n-17) -2078573014*a(n-18) +2309819561*a(n-19) -2991164305*a(n-20) +2465714727*a(n-21) -3427669017*a(n-22) +1906150182*a(n-23) -2939880630*a(n-24) +1350797248*a(n-25) -1313333555*a(n-26) +1690232897*a(n-27) +1046282076*a(n-28) +2849146517*a(n-29) +3075606987*a(n-30) +3774538533*a(n-31) +3807731593*a(n-32) +3631581833*a(n-33) +3191721534*a(n-34) +2593241832*a(n-35) +1979588333*a(n-36) +1403683196*a(n-37) +935210902*a(n-38) +582152845*a(n-39) +339405509*a(n-40) +185220493*a(n-41) +94342890*a(n-42) +44863967*a(n-43) +19830162*a(n-44) +8128055*a(n-45) +3075933*a(n-46) +1067442*a(n-47) +337750*a(n-48) +96306*a(n-49) +24424*a(n-50) +5412*a(n-51) +1012*a(n-52) +153*a(n-53) +17*a(n-54) +a(n-55)

Example

Some solutions for n=4
..6..6....0..0....1..1....3..3....0..0....2..2....5..5....6..6....4..4....4..4
..6..6....1..1....5..5....3..3....6..6....2..2....5..5....6..6....4..4....4..4
..5..5....1..1....5..5....3..3....6..6....3..3....5..5....5..5....6..6....1..1
..1..1....0..0....5..5....1..1....1..1....3..3....5..5....0..0....6..6....1..1

Crossrefs

Sequence in context: A225013 A228459 A203059 * A293887 A224131 A218266

Adjacent sequences: A203380 A203381 A203382 * A203384 A203385 A203386

Keyword

nonn

Author

R. H. Hardin Jan 01 2012

Status

approved