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A245873
Number of length 4+2 0..n arrays with some pair in every consecutive three terms totalling exactly n.
1
26, 239, 676, 1629, 3102, 5515, 8840, 13625, 19810, 28071, 38316, 51349, 67046, 86339, 109072, 136305, 167850, 204895, 247220, 296141, 351406, 414459, 485016, 564649, 653042, 751895, 860860, 981765, 1114230, 1260211, 1419296, 1593569
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - a(n-2) - 5*a(n-3) + 5*a(n-4) + a(n-5) - 3*a(n-6) + a(n-7).
Conjectures from Colin Barker, Nov 04 2018: (Start)
G.f.: x*(26 + 161*x - 15*x^2 - 30*x^3 - 44*x^4 - 3*x^5 + x^6) / ((1 - x)^5*(1 + x)^2).
a(n) = 1 + 7*n + 20*n^2 + 16*n^3 + n^4 for n even.
a(n) = -8 - 3*n + 20*n^2 + 16*n^3 + n^4 for n odd.
(End)
EXAMPLE
Some solutions for n=10:
0 6 8 3 8 4 7 8 7 1 8 10 4 3 7 1
10 5 6 10 6 2 3 9 4 0 1 2 5 3 4 0
4 4 4 0 4 6 3 1 3 10 9 8 5 7 6 10
6 5 10 7 4 8 7 1 7 1 3 7 3 3 10 0
1 5 0 10 6 2 6 9 8 0 7 3 7 1 0 4
4 8 7 0 0 0 4 7 3 10 7 4 9 7 9 10
CROSSREFS
Row 4 of A245869.
Sequence in context: A196638 A163726 A293614 * A275880 A020537 A184461
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 04 2014
STATUS
approved