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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
OFFSET
1,1
LINKS
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: A114039 A090305 A358145 * A304317 A351918 A326272
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 02 2014
STATUS
approved