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A262912 Number of (n+1)X(3+1) 0..1 arrays with each row divisible by 3 and each column divisible by 7, read as a binary number with top and left being the most significant bits. 1
1, 6, 15, 53, 318, 1207, 5797, 34782, 189135, 1089701, 6538206, 38547751, 229660021, 1377960126, 8242589055, 49395098933, 296370593598, 1777250964247, 10661181588037, 63967089528222, 383764138693935, 2302493636842181 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 3 of A262917.

LINKS

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

Robert Israel, Maple-assisted proof of empirical formula for A262912

FORMULA

Empirical: a(n) = 8*a(n-1) -16*a(n-2) +104*a(n-3) -640*a(n-4) +1280*a(n-5) -3830*a(n-6) +15280*a(n-7) -30560*a(n-8) +58240*a(n-9) -99200*a(n-10) +198400*a(n-11) -283209*a(n-12) -115128*a(n-13) +230256*a(n-14) -345384*a(n-15).

Empirical formula verified: see link. - Robert Israel, Aug 12 2019

EXAMPLE

Some solutions for n=4

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

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

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

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

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

CROSSREFS

Cf. A262917.

Sequence in context: A271332 A244024 A122365 * A119132 A073065 A190801

Adjacent sequences:  A262909 A262910 A262911 * A262913 A262914 A262915

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 04 2015

STATUS

approved

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Last modified July 4 17:39 EDT 2022. Contains 355083 sequences. (Running on oeis4.)