The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A283635 Number of 2 X n 0..1 arrays with no 1 equal to more than one of its horizontal, diagonal and antidiagonal neighbors, with the exception of exactly two elements. 1
 0, 0, 0, 36, 88, 516, 2076, 7372, 27108, 92436, 308980, 1013112, 3250572, 10288376, 32139960, 99287748, 303857760, 922134588, 2777950524, 8314125460, 24737931132, 73218906420, 215681560092, 632587894224, 1848037669164, 5379301732896 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 5*a(n-3) - 42*a(n-4) - 33*a(n-5) + 51*a(n-6) + 156*a(n-7) + 144*a(n-8) + 64*a(n-9). Empirical g.f.: 4*x^4*(9 - 5*x + 9*x^2 + 45*x^3) / (1 - x - 3*x^2 - 4*x^3)^3. - Colin Barker, Feb 21 2019 EXAMPLE Some solutions for n=4: ..0..1..1..1. .0..0..0..1. .1..1..0..0. .1..1..1..1. .1..0..1..0 ..1..0..0..0. .1..1..1..0. .1..0..1..1. .1..0..0..1. .0..1..0..1 CROSSREFS Row 2 of A283634. Sequence in context: A043963 A044174 A044555 * A305068 A182467 A060936 Adjacent sequences:  A283632 A283633 A283634 * A283636 A283637 A283638 KEYWORD nonn AUTHOR R. H. Hardin, Mar 12 2017 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 3 15:35 EST 2020. Contains 338906 sequences. (Running on oeis4.)