A228735 Number of arrays of the median of three adjacent elements of some length -(n+2) 0..3 array.

4, 16, 64, 232, 696, 2072, 6130, 18378, 55716, 169734, 517764, 1578184, 4806344, 14629384, 44519552, 135480532, 412314438, 1254882280, 3819338704, 11624541548, 35380360780, 107682931160, 327740673246, 997501106370, 3035962621026

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) -2*a(n-2) -6*a(n-3) +6*a(n-4) +15*a(n-5) -11*a(n-6) +a(n-7) +a(n-8) +3*a(n-9) +24*a(n-10) -3*a(n-11) -35*a(n-12) -28*a(n-13) +22*a(n-14) +18*a(n-15) -9*a(n-16) -11*a(n-17) -4*a(n-18) +15*a(n-19) +15*a(n-20) -2*a(n-21) -4*a(n-22) -4*a(n-23) -3*a(n-24) +a(n-25) +a(n-26)

Example

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

Crossrefs

Column 3 of A228740.

Sequence in context: A248089 A248088 A294037 * A289694 A232425 A375865

Adjacent sequences: A228732 A228733 A228734 * A228736 A228737 A228738

Keyword

nonn

Author

R. H. Hardin Sep 01 2013

Status

approved