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A246475 Number of length n+3 0..4 arrays with no pair in any consecutive four terms totalling exactly 4. 1
172, 484, 1376, 3904, 11020, 31104, 87888, 248568, 702724, 1985932, 5612156, 15862556, 44837136, 126731180, 358188232, 1012377900, 2861418780, 8087637712, 22859103016, 64609341900, 182613147216, 516142417472, 1458837964296 (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) = 2*a(n-1) + a(n-3) + 14*a(n-4) + 3*a(n-5) + 6*a(n-6) + a(n-8) + a(n-9).

Empirical g.f.: 4*x*(43 + 35*x + 102*x^2 + 245*x^3 + 80*x^4 + 99*x^5 + 7*x^6 + 21*x^7 + 16*x^8) / (1 - 2*x - x^3 - 14*x^4 - 3*x^5 - 6*x^6 - x^8 - x^9). - Colin Barker, Nov 06 2018

EXAMPLE

Some solutions for n=6:

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

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

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

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

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

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

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

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

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

CROSSREFS

Column 4 of A246479.

Sequence in context: A056132 A261706 A043387 * A202641 A234998 A234992

Adjacent sequences:  A246472 A246473 A246474 * A246476 A246477 A246478

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 27 2014

STATUS

approved

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Last modified May 19 03:44 EDT 2022. Contains 353826 sequences. (Running on oeis4.)