A229007 Number of arrays of median of three adjacent elements of some length n+2 0..3 array, with no adjacent equal elements in the latter.

4, 14, 46, 130, 332, 830, 2054, 5108, 12790, 32146, 80942, 203898, 513498, 1292934, 3254868, 8193210, 20623908, 51914372, 130680214, 328953874, 828059138, 2084434524, 5247046924, 13208134738, 33248182980, 83693989466, 210678694852

Offset: 1

Author

R. H. Hardin, Sep 10 2013

Keywords

• nonn

Comments

Column 3 of A229012.

Examples

			Some solutions for n=4
..2....2....2....1....3....3....1....2....2....3....2....1....2....2....2....1
..0....2....2....2....1....2....2....3....2....2....3....0....2....2....2....3
..1....1....3....0....2....2....3....2....2....1....1....3....1....1....0....0
..1....3....0....3....1....2....2....2....1....1....2....0....2....1....3....1
		

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -5*a(n-3) +2*a(n-4) +11*a(n-5) -11*a(n-6) -2*a(n-7) +19*a(n-8) -8*a(n-9) -13*a(n-10) +28*a(n-11) -18*a(n-12) +a(n-13) +26*a(n-14) -24*a(n-15) +9*a(n-16) +15*a(n-17) -21*a(n-18) +13*a(n-19) +5*a(n-20) -12*a(n-21) +19*a(n-22) -9*a(n-23) -a(n-24) +4*a(n-25) -4*a(n-26) +2*a(n-27).