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A256820 Number of length n+5 0..1 arrays with at most two downsteps in every n consecutive neighbor pairs. 1
64, 128, 256, 512, 956, 1656, 2693, 4158, 6153, 8792, 12202, 16524, 21914, 28544, 36603, 46298, 57855, 71520, 87560, 106264, 127944, 152936, 181601, 214326, 251525, 293640, 341142, 394532, 454342, 521136, 595511, 678098, 769563, 870608, 981972 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Row 5 of A256816.
LINKS
FORMULA
Empirical: a(n) = (1/120)*n^5 + (1/6)*n^4 + (175/24)*n^3 - (103/6)*n^2 + (747/10)*n - 30 for n>3.
Empirical g.f.: x*(64 - 256*x + 448*x^2 - 384*x^3 + 124*x^4 + 16*x^5 - 7*x^6 - 8*x^7 + 4*x^8) / (1 - x)^6. - Colin Barker, Jan 21 2018
EXAMPLE
Some solutions for n=4:
..0....1....0....0....0....1....0....1....0....1....1....0....1....1....0....1
..0....0....0....1....0....0....0....1....1....0....1....0....0....0....0....0
..0....0....0....0....1....1....0....0....1....1....1....0....1....0....1....1
..1....0....0....0....0....1....1....0....0....1....0....0....1....1....1....0
..1....0....1....1....0....1....1....1....0....0....1....1....1....1....1....1
..0....1....0....0....0....1....1....1....0....1....0....1....0....1....0....1
..1....1....1....1....0....1....0....0....0....0....1....1....1....0....1....0
..1....0....0....1....0....0....0....1....0....0....0....1....0....1....0....1
..1....1....0....0....0....0....1....0....0....1....1....1....1....1....1....0
CROSSREFS
Cf. A256816.
Sequence in context: A172420 A069493 A076470 * A031464 A045076 A235058
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2015
STATUS
approved

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Last modified July 13 04:46 EDT 2024. Contains 374267 sequences. (Running on oeis4.)