A183906 Number of nondecreasing arrangements of n+2 numbers in 0..3 with each number being the sum mod 4 of two others.

2, 5, 17, 38, 67, 105, 153, 212, 283, 367, 465, 578, 707, 853, 1017, 1200, 1403, 1627, 1873, 2142, 2435, 2753, 3097, 3468, 3867, 4295, 4753, 5242, 5763, 6317, 6905, 7528, 8187, 8883, 9617, 10390, 11203, 12057, 12953, 13892, 14875, 15903, 16977, 18098

Offset

1,1

Comments

Column 3 of A183912.

Links

R. H. Hardin, Table of n, a(n) for n = 1..199

Formula

Empirical: a(n) = (1/6)*n^3 + 2*n^2 + (5/6)*n - 8 for n>2.

Conjectures from Colin Barker, Apr 05 2018: (Start)

G.f.: x*(2 - 3*x + 9*x^2 - 8*x^3 - x^4 + 2*x^5) / (1 - x)^4.

a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) for n>6.

(End)

Example

All solutions for n=2:
..1....0....0....0....1
..1....0....0....2....2
..2....0....2....2....3
..3....0....2....2....3

Crossrefs

Cf. A183912.

Sequence in context: A127436 A064168 A118727 * A042361 A114300 A099207

Adjacent sequences: A183903 A183904 A183905 * A183907 A183908 A183909

Keyword

nonn

Author

R. H. Hardin, Jan 07 2011

Status

approved