A249987 Number of length 7+1 0..2*n arrays with the sum of the absolute values of adjacent differences equal to 7*n

1012, 31380, 245860, 1293326, 4598532, 14027522, 35380112, 82176822, 170479400, 335836428, 613774848, 1082535196, 1809905436, 2948384694, 4614428112, 7080133636, 10530399420, 15419165316, 22022418940, 31058475666, 42919172164

Offset

1,1

Comments

Row 7 of A249982

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +5*a(n-2) -12*a(n-3) -9*a(n-4) +30*a(n-5) +5*a(n-6) -40*a(n-7) +5*a(n-8) +30*a(n-9) -9*a(n-10) -12*a(n-11) +5*a(n-12) +2*a(n-13) -a(n-14)

Empirical for n mod 2 = 0: a(n) = (459901/26880)*n^7 + (238219/1920)*n^6 + (682979/1920)*n^5 + (30971/64)*n^4 + (124069/480)*n^3 + (337/240)*n^2 + (10541/420)*n

Empirical for n mod 2 = 1: a(n) = (459901/26880)*n^7 + (238219/1920)*n^6 + (86757/256)*n^5 + (50735/128)*n^4 + (513337/3840)*n^3 - (25939/1920)*n^2 + (87707/5376)*n - (119/128)

Example

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

Crossrefs

Sequence in context: A023058 A223077 A206191 * A224920 A022054 A107518

Adjacent sequences: A249984 A249985 A249986 * A249988 A249989 A249990

Keyword

nonn

Author

R. H. Hardin, Nov 10 2014

Status

approved