A183910 Number of nondecreasing arrangements of n+2 numbers in 0..7 with each number being the sum mod 8 of two others.

2, 5, 40, 207, 778, 2199, 5126, 10501, 19630, 34274, 56754, 90071, 138042, 205453, 298230, 423629, 590446, 809248, 1092626, 1455471, 1915274, 2492451, 3210694, 4097349, 5183822, 6506014, 8104786, 10026455, 12323322, 15054233, 18285174

Offset

1,1

Comments

Column 7 of A183912.

Links

R. H. Hardin, Table of n, a(n) for n = 1..61

Formula

Empirical: a(n) = (1/5040)*n^7 + (1/120)*n^6 + (53/360)*n^5 + (17/12)*n^4 - (1313/720)*n^3 - (1777/40)*n^2 + (14876/105)*n - 83 for n>3.

Conjectures from Colin Barker, Apr 06 2018: (Start)

G.f.: x*(2 - 11*x + 56*x^2 - 85*x^3 + 102*x^4 - 231*x^5 + 302*x^6 - 129*x^7 - 44*x^8 + 49*x^9 - 10*x^10) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>10.

(End)

Example

All solutions for n=2:
..0....2....2....0....0
..0....2....4....0....4
..0....4....6....4....4
..0....6....6....4....4

Crossrefs

Cf. A183912.

Sequence in context: A155176 A127974 A012801 * A162035 A366358 A245242

Adjacent sequences: A183907 A183908 A183909 * A183911 A183912 A183913

Keyword

nonn

Author

R. H. Hardin, Jan 07 2011

Status

approved