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A245865
Number of length n+2 0..4 arrays with some pair in every consecutive three terms totalling exactly 4.
1
61, 193, 549, 1629, 4753, 13961, 40901, 119953, 351649, 1031057, 3022933, 8863117, 25986061, 76189749, 223384017, 654949861, 1920277409, 5630150189, 16507298221, 48398515249, 141901859897, 416048676085, 1219832512513, 3576483842281
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + a(n-2) - a(n-3) - 5*a(n-4) - 8*a(n-5) + 3*a(n-6).
Empirical g.f.: x*(61 + 10*x - 91*x^2 - 150*x^3 - 185*x^4 + 75*x^5) / (1 - 3*x - x^2 + x^3 + 5*x^4 + 8*x^5 - 3*x^6). - Colin Barker, Nov 04 2018
EXAMPLE
Some solutions for n=8:
1 1 0 4 1 3 2 0 0 0 1 4 2 2 1 3
2 4 1 1 0 0 2 1 2 4 0 0 3 2 3 0
3 0 3 3 4 4 0 3 2 4 3 1 1 0 1 4
2 4 1 0 3 0 4 1 1 0 1 4 2 4 2 2
2 4 1 4 1 3 2 2 2 4 1 0 3 0 2 2
0 0 3 0 3 1 2 2 3 2 3 3 1 1 2 0
2 4 3 4 2 0 0 4 1 2 4 1 0 3 2 4
2 3 1 0 1 3 2 0 3 1 0 4 4 1 4 3
0 1 3 4 2 1 2 2 4 3 1 0 0 4 0 0
2 4 1 3 2 3 4 2 1 3 4 1 1 0 4 1
CROSSREFS
Column 4 of A245869.
Sequence in context: A121513 A139508 A364716 * A357780 A259410 A234925
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 04 2014
STATUS
approved