A212781 Half the number of 0..7 arrays of length n+2 with second differences nonzero.

240, 1803, 13544, 101743, 764297, 5741427, 43129809, 323992699, 2433844978, 18283132290, 137343556947, 1031729811702, 7750391995200, 58221227493827, 437359985531993, 3285464171376777, 24680526747938834, 185401017567775934

Offset: 1

Author

R. H. Hardin May 27 2012

Keywords

• nonn

Comments

Column 7 of A212782

Examples

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

Links

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

Formula

Empirical: a(n) = 4*a(n-1) +22*a(n-2) +33*a(n-3) +5*a(n-4) -36*a(n-5) -40*a(n-6) -28*a(n-7) -53*a(n-8) -73*a(n-9) -37*a(n-10) +12*a(n-11) +32*a(n-12) +39*a(n-13) +28*a(n-14) +6*a(n-15)