A245999 Number of length 4+2 0..n arrays with no pair in any consecutive three terms totalling exactly n.

2, 26, 396, 2196, 9582, 29790, 80504, 185192, 391290, 753570, 1371972, 2352636, 3877286, 6128486, 9405552, 13997520, 20363634, 28934442, 40377980, 55306340, 74651742, 99252846, 130367976, 169112376, 217138922, 275894450, 347501364

Offset: 1

Author

R. H. Hardin, Aug 09 2014

Keywords

• nonn

Comments

Row 4 of A245995.

Examples

			Some solutions for n=8
..1....2....1....3....2....0....0....1....1....0....4....0....2....5....5....3
..4....7....3....2....0....2....2....5....1....7....1....2....2....2....2....7
..5....5....4....1....7....1....5....5....5....6....6....3....7....1....5....7
..6....5....1....4....2....8....4....7....8....5....3....4....7....8....7....5
..8....0....5....0....2....1....8....7....4....4....6....1....4....5....0....2
..4....1....6....1....7....8....7....4....6....7....1....1....7....5....6....2
		

Links

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

Crossrefs

Cf. A245995.

Formula

Empirical: a(n) = 3*a(n-1) +a(n-2) -11*a(n-3) +6*a(n-4) +14*a(n-5) -14*a(n-6) -6*a(n-7) +11*a(n-8) -a(n-9) -3*a(n-10) +a(n-11).

Empirical: G.f.: -2*x*(1 +10*x +158*x^2 +502*x^3 +1436*x^4 +1510*x^5 +1498*x^6 +474*x^7 +171*x^8) / ( (1+x)^4*(x-1)^7 ). - R. J. Mathar, Aug 10 2014