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A256819 Number of length n+4 0..1 arrays with at most two downsteps in every n consecutive neighbor pairs. 1
32, 64, 128, 256, 484, 856, 1424, 2249, 3402, 4965, 7032, 9710, 13120, 17398, 22696, 29183, 37046, 46491, 57744, 71052, 86684, 104932, 126112, 150565, 178658, 210785, 247368, 288858, 335736, 388514, 447736, 513979, 587854, 670007, 761120, 861912 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A256816.

LINKS

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

FORMULA

Empirical: a(n) = (1/120)*n^5 + (1/8)*n^4 + (27/8)*n^3 - (65/8)*n^2 + (1897/60)*n + 3 for n>2.

Empirical g.f.: x*(32 - 128*x + 224*x^2 - 192*x^3 + 68*x^4 - 4*x^6 + x^7) / (1 - x)^6. - Colin Barker, Jan 21 2018

EXAMPLE

Some solutions for n=4:

..1....1....1....0....0....1....0....1....1....0....0....1....0....0....0....0

..0....0....0....1....0....0....1....1....1....0....0....0....1....0....1....1

..0....1....0....1....0....0....0....0....0....0....1....1....1....0....1....1

..1....1....0....1....1....0....0....0....0....0....0....1....0....0....1....0

..1....0....0....1....1....0....0....1....0....0....0....0....1....1....1....1

..0....0....0....0....1....0....0....0....0....0....0....1....1....1....0....0

..0....0....0....1....0....1....1....0....1....0....0....1....1....0....1....1

..1....1....1....0....1....1....0....1....1....1....1....0....1....0....1....0

CROSSREFS

Cf. A256816.

Sequence in context: A172419 A069492 A076469 * A235057 A249116 A110562

Adjacent sequences:  A256816 A256817 A256818 * A256820 A256821 A256822

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 10 2015

STATUS

approved

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Last modified May 25 11:07 EDT 2020. Contains 334592 sequences. (Running on oeis4.)