The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A209367 Number of n X 1 1..3 arrays with no element with value z exactly a city block distance of z from another element with value z. 1
 3, 8, 19, 35, 64, 110, 185, 322, 599, 1084, 1902, 3280, 5816, 10425, 18711, 33023, 58229, 102865, 183340, 326023, 578770, 1023268, 1814036, 3218397, 5719285, 10142300, 17984603, 31872737, 56560901, 100345791, 178058874, 315719677 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A209374. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = a(n-2) + 4*a(n-4) + 4*a(n-5) + 5*a(n-6) - a(n-7) - 5*a(n-8) - 5*a(n-9) - 5*a(n-10) + a(n-11) + 2*a(n-12) for n>14. Empirical g.f.: x*(3 + 8*x + 16*x^2 + 27*x^3 + 33*x^4 + 31*x^5 - 2*x^6 - 41*x^7 - 54*x^8 - 35*x^9 - 12*x^10 - 11*x^11 - 9*x^12 - 2*x^13) / ((1 - x)*(1 + x - 4*x^4 - 8*x^5 - 13*x^6 - 12*x^7 - 7*x^8 - 2*x^9 + 3*x^10 + 2*x^11)). - Colin Barker, Jul 09 2018 EXAMPLE All solutions for n=5: ..2....1....2....3....3....2....3....3....3....2....1....2....3....3 ..3....3....1....3....2....1....1....1....2....3....2....3....1....3 ..1....1....3....1....3....3....2....2....2....3....2....1....2....1 ..2....2....3....2....1....3....2....1....1....2....3....2....2....2 ..1....1....2....2....3....1....1....3....3....2....3....2....3....1 CROSSREFS Cf. A209374. Sequence in context: A184444 A139020 A147358 * A086167 A083186 A055341 Adjacent sequences: A209364 A209365 A209366 * A209368 A209369 A209370 KEYWORD nonn AUTHOR R. H. Hardin, Mar 07 2012 STATUS approved

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

Last modified September 27 17:53 EDT 2023. Contains 365714 sequences. (Running on oeis4.)