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.

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

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

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

Adjacent sequences: A281692 A281693 A281694 * A281696 A281697 A281698

Keyword

nonn

Author

R. H. Hardin, Jan 27 2017

Status

approved