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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A270852 Number of 3X3X3 triangular 0..n arrays with some element plus some adjacent element totalling n+1, n or n-1 exactly once. 1

%I #4 Mar 24 2016 08:39:36

%S 0,0,30,270,1650,7344,24954,68838,164454,347916,677130,1219626,

%T 2083038,3373728,5268642,7918158,11590422,16482708,22978554,31322706,

%U 42040590,55422696,72165138,92600118,117625542,147608988,183683562,226243578

%N Number of 3X3X3 triangular 0..n arrays with some element plus some adjacent element totalling n+1, n or n-1 exactly once.

%C Row 3 of A270850.

%H R. H. Hardin, <a href="/A270852/b270852.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) +3*a(n-2) -8*a(n-3) -2*a(n-4) +12*a(n-5) -2*a(n-6) -8*a(n-7) +3*a(n-8) +2*a(n-9) -a(n-10) for n>17

%F Empirical for n mod 2 = 0: a(n) = 27*n^5 - 531*n^4 + 4794*n^3 - 24417*n^2 + 69189*n - 86274 for n>7

%F Empirical for n mod 2 = 1: a(n) = 27*n^5 - 531*n^4 + 4806*n^3 - 24624*n^2 + 70425*n - 88833 for n>7

%e Some solutions for n=4

%e ....4......0......4......4......2......2......1......2......0......2......2

%e ...3.4....0.1....4.4....4.4....0.0....1.0....1.0....2.0....2.2....1.0....4.4

%e ..2.4.3..0.2.0..3.2.4..2.2.4..0.2.1..1.0.0..2.0.0..0.0.2..0.0.0..1.1.0..4.3.2

%Y Cf. A270850.

%K nonn

%O 1,3

%A _R. H. Hardin_, Mar 24 2016

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 15 18:28 EDT 2024. Contains 371696 sequences. (Running on oeis4.)