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A246739 Number of length 2+4 0..n arrays with no pair in any consecutive five terms totalling exactly n. 1
2, 16, 260, 1096, 5430, 15960, 47432, 109552, 246890, 483520, 920652, 1606776, 2735390, 4392136, 6907280, 10419040, 15447762, 22202352, 31455380, 43507240, 59453702, 79710136, 105775320, 138205776, 178991930, 228860320, 290390492 (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) = 3*a(n-1) + a(n-2) - 11*a(n-3) + 6*a(n-4) + 14*a(n-5) - 14*a(n-6) - 6*a(n-7) + 11*a(n-8) - a(n-9) - 3*a(n-10) + a(n-11).

Conjectures from Colin Barker, Nov 06 2018: (Start)

G.f.: 2*x*(1 + 5*x + 105*x^2 + 161*x^3 + 1023*x^4 + 655*x^5 + 2211*x^6 + 523*x^7 + 1076*x^8) / ((1 - x)^7*(1 + x)^4).

a(n) = -58*n + 111*n^2 - 87*n^3 + 36*n^4 - 8*n^5 + n^6 for n even.

a(n) = -70 + 80*n + 34*n^2 - 71*n^3 + 36*n^4 - 8*n^5 + n^6 for n odd.

(End)

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

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

CROSSREFS

Row 2 of A246737.

Sequence in context: A140307 A114039 A090305 * A304317 A283685 A197458

Adjacent sequences:  A246736 A246737 A246738 * A246740 A246741 A246742

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 02 2014

STATUS

approved

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Last modified January 19 07:43 EST 2019. Contains 319305 sequences. (Running on oeis4.)