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A304468
Number of nX4 0..1 arrays with every element unequal to 0, 1, 2, 3 or 6 king-move adjacent elements, with upper left element zero.
1
8, 49, 117, 322, 1100, 2957, 8254, 26698, 77788, 221123, 681855, 2041108, 5932703, 17889612, 53854606, 158987996, 475744589, 1430898909, 4260906900, 12733223515, 38231707572, 114317071912, 341873189152, 1025366065205, 3071359996945
OFFSET
1,1
COMMENTS
Column 4 of A304472.
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) -17*a(n-2) +34*a(n-3) -113*a(n-4) +204*a(n-5) -132*a(n-6) +220*a(n-7) -539*a(n-8) +180*a(n-9) +308*a(n-10) +84*a(n-11) -56*a(n-12) -532*a(n-13) +370*a(n-14) -87*a(n-15) +214*a(n-16) -176*a(n-17) +38*a(n-18) -20*a(n-19) +18*a(n-20) -4*a(n-21) for n>25
EXAMPLE
Some solutions for n=5
..0..0..0..0. .0..0..1..0. .0..0..1..1. .0..1..1..1. .0..0..1..0
..1..1..1..1. .1..0..1..1. .0..0..0..1. .1..0..1..1. .0..0..1..1
..1..1..1..1. .1..1..1..1. .0..1..1..1. .1..0..1..1. .0..0..0..0
..0..1..1..1. .0..0..1..1. .0..0..1..1. .1..0..1..1. .0..0..0..0
..0..0..1..1. .1..0..1..0. .1..1..1..0. .0..1..1..0. .1..1..1..1
CROSSREFS
Cf. A304472.
Sequence in context: A304771 A316514 A352179 * A272713 A316285 A018200
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 13 2018
STATUS
approved