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A280898
Number of nX4 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
1
1, 213, 22568, 1451655, 75809243, 3521886844, 151803173493, 6210239609889, 244458357395448, 9341978860523675, 348715442831794031, 12770615176465927916, 460340220926625794761, 16373994793450266278677
OFFSET
1,2
COMMENTS
Column 4 of A280902.
LINKS
FORMULA
Empirical: a(n) = 87*a(n-1) -2391*a(n-2) +16652*a(n-3) +109659*a(n-4) +121533*a(n-5) -306694*a(n-6) -726651*a(n-7) -13365*a(n-8) +1128492*a(n-9) +688905*a(n-10) -531441*a(n-11) -531441*a(n-12) for n>14
EXAMPLE
Some solutions for n=3
..0..1..1..1. .0..1..0..0. .0..1..0..0. .0..1..1..2. .0..0..0..1
..2..0..1..2. .0..2..2..2. .2..2..0..1. .2..1..0..2. .2..0..2..1
..0..2..1..1. .0..1..1..1. .1..0..2..0. .1..2..1..2. .2..1..2..0
CROSSREFS
Cf. A280902.
Sequence in context: A212312 A201342 A092796 * A180395 A242793 A335721
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 10 2017
STATUS
approved