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A281695
Number of 3Xn 0..2 arrays with no element equal to more than one of its horizontal, diagonal or antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.
1
0, 15, 847, 14575, 172398, 1900616, 17698286, 154129813, 1275251254, 10132993005, 78117611504, 587910877987, 4338607753232, 31501834570803, 225621916093246, 1597186816890237, 11193139375201572, 77755257717795413, 535979713724257216
OFFSET
1,2
COMMENTS
Row 3 of A281693.
LINKS
FORMULA
Empirical: a(n) = 17*a(n-1) -102*a(n-2) +327*a(n-3) -1122*a(n-4) +3306*a(n-5) -6463*a(n-6) +19106*a(n-7) -17295*a(n-8) +69491*a(n-9) -5686*a(n-10) +146028*a(n-11) +128697*a(n-12) +149517*a(n-13) +324330*a(n-14) -39179*a(n-15) +190705*a(n-16) -146256*a(n-17) -775732*a(n-18) -287653*a(n-19) -61287*a(n-20) -624068*a(n-21) -190577*a(n-22) +872472*a(n-23) +455292*a(n-24) -159861*a(n-25) +323130*a(n-26) +380599*a(n-27) -313277*a(n-28) -413976*a(n-29) +16356*a(n-30) +58782*a(n-31) -94092*a(n-32) -9164*a(n-33) +96964*a(n-34) +44568*a(n-35) -23024*a(n-36) -19832*a(n-37) -672*a(n-38) +2432*a(n-39) +512*a(n-40) for n>45
EXAMPLE
Some solutions for n=4
..0..1..0..2. .0..1..1..1. .0..1..1..0. .0..1..2..0. .0..1..0..1
..0..1..1..2. .0..1..2..1. .1..2..1..2. .2..2..0..1. .0..2..2..0
..1..2..1..0. .2..2..2..1. .2..2..1..0. .1..1..2..2. .0..0..1..2
CROSSREFS
Cf. A281693.
Sequence in context: A261828 A205432 A020240 * A223276 A233019 A270962
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 27 2017
STATUS
approved