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A258732 Number of length n+2 0..3 arrays with at most one downstep in every n consecutive neighbor pairs. 1
64, 225, 608, 1408, 2936, 5664, 10280, 17754, 29416, 47047, 72984, 110240, 162640, 234974, 333168, 464474, 637680, 863341, 1154032, 1524624, 1992584, 2578300, 3305432, 4201290, 5297240, 6629139, 8237800, 10169488, 12476448, 15217466 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 2 of A258730.

LINKS

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

FORMULA

Empirical: a(n) = (1/5040)*n^7 + (1/120)*n^6 + (53/360)*n^5 + (5/4)*n^4 + (5167/720)*n^3 + (2489/120)*n^2 + (2591/105)*n + 10.

Empirical g.f.: x*(64 - 287*x + 600*x^2 - 740*x^3 + 576*x^4 - 282*x^5 + 80*x^6 - 10*x^7) / (1 - x)^8. - Colin Barker, Jan 26 2018

EXAMPLE

Some solutions for n=4:

..0....2....2....1....1....0....2....1....3....0....2....0....1....1....0....1

..0....2....2....1....0....0....3....2....0....2....3....0....1....1....2....1

..1....3....2....2....1....3....1....3....1....2....3....3....3....2....2....3

..2....3....2....3....1....0....1....1....1....1....0....2....0....2....3....0

..1....3....3....0....1....1....2....1....2....2....1....3....0....0....3....1

..3....0....0....0....0....2....3....1....2....3....3....3....0....0....0....3

CROSSREFS

Cf. A258730.

Sequence in context: A295021 A194932 A016994 * A279714 A228802 A222547

Adjacent sequences:  A258729 A258730 A258731 * A258733 A258734 A258735

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 08 2015

STATUS

approved

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Last modified December 13 06:26 EST 2019. Contains 329968 sequences. (Running on oeis4.)