A255667 Number of length n+7 0..3 arrays with at most two downsteps in every n consecutive neighbor pairs

65536, 262144, 1020000, 3083292, 7323894, 15269184, 29577432, 53275408, 90990131, 149141772, 236469626, 364664160, 549120490, 809830656, 1172434356, 1669450392, 2341713998, 3240048488, 4427203308, 5980094628, 7992389097

Offset

1,1

Comments

Row 7 of A255660

Links

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

Formula

Empirical: a(n) = (1/39916800)*n^11 + (13/3628800)*n^10 + (1/4320)*n^9 + (211/24192)*n^8 + (1428221/1209600)*n^7 + (5660089/172800)*n^6 + (145503607/362880)*n^5 + (63892553/36288)*n^4 + (439312849/7200)*n^3 - (2124832139/12600)*n^2 + (67026258/385)*n - 159592 for n>5

Example

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

Crossrefs

Cf. A255660

Sequence in context: A069277 A202932 A258737 * A242323 A016784 A016808

Adjacent sequences: A255664 A255665 A255666 * A255668 A255669 A255670

Keyword

nonn

Author

R. H. Hardin, Mar 01 2015

Status

approved