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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 1
2, 40, 1675, 81440, 4059950, 203087097, 10164141586, 508740409496, 25464106707391, 1274565023173456, 63796351813851410, 3193226785065121249, 159831987739494226958, 8000141016276333546184, 400434589880788614683443 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 3 21:33 EST 2022. Contains 358543 sequences. (Running on oeis4.)