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A248430 Number of length n+2 0..5 arrays with every three consecutive terms having the sum of some two elements equal to twice the third. 1
42, 70, 118, 198, 342, 590, 1014, 1766, 3062, 5286, 9222, 16006, 27654, 48262, 83782, 144774, 252678, 438662, 758022, 1323014, 2296838, 3969030, 6927366, 12026374, 20782086, 36272134, 62970886, 108816390, 189923334, 329719814, 569769990 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 6*a(n-3) - 6*a(n-4) - 4*a(n-6) + 4*a(n-7).

Empirical g.f.: 2*x*(21 + 14*x + 24*x^2 - 86*x^3 - 12*x^4 - 20*x^5 + 56*x^6) / ((1 - x)*(1 - 6*x^3 + 4*x^6)). - Colin Barker, Nov 08 2018

EXAMPLE

Some solutions for n=6:

..2....0....4....1....1....5....3....5....1....0....5....2....5....4....5....2

..0....1....0....3....2....1....1....3....5....2....4....1....1....0....1....4

..1....2....2....2....3....3....2....4....3....1....3....3....3....2....3....0

..2....3....4....4....1....2....3....5....4....3....2....5....5....1....2....2

..0....4....0....3....2....1....4....3....5....2....1....1....1....3....4....1

..4....2....2....5....3....3....5....1....3....4....0....3....3....5....3....3

..2....3....1....1....1....2....3....2....4....3....2....5....5....4....2....2

..3....1....0....3....2....4....4....0....2....2....4....1....4....3....4....1

CROSSREFS

Column 5 of A248433.

Sequence in context: A192274 A291319 A226168 * A305153 A261621 A043689

Adjacent sequences:  A248427 A248428 A248429 * A248431 A248432 A248433

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 06 2014

STATUS

approved

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Last modified October 14 04:44 EDT 2019. Contains 327995 sequences. (Running on oeis4.)