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A212776 Half the number of 0..2 arrays of length n+2 with second differences nonzero 1
11, 27, 66, 162, 397, 973, 2385, 5846, 14329, 35122, 86088, 211011, 517211, 1267741, 3107372, 7616509, 18668898, 45759514, 112161581, 274920321, 673859821, 1651704234, 4048508001, 9923336574, 24323184920, 59618790539, 146132186103 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 2 of A212782
LINKS
FORMULA
Empirical: a(n) = a(n-1) +2*a(n-2) +3*a(n-3) +2*a(n-4).
Empirical: G.f. -x*(11+16*x+17*x^2+9*x^3) / ( -1+x+2*x^2+3*x^3+2*x^4 ). - R. J. Mathar, Jul 01 2013
EXAMPLE
Some solutions for n=5
..2....0....1....1....1....2....0....1....0....0....1....2....0....0....1....2
..0....2....1....2....1....2....1....2....2....2....2....1....2....0....0....0
..0....1....0....0....0....1....0....1....0....1....1....1....0....2....2....0
..1....2....0....1....1....1....2....2....0....2....2....2....2....1....0....2
..1....0....2....1....0....0....1....0....1....0....0....0....0....1....1....0
..2....1....1....0....2....0....2....1....0....2....2....1....2....0....0....1
..0....1....2....0....1....1....1....0....0....2....1....0....1....2....1....1
CROSSREFS
Sequence in context: A106839 A044072 A044453 * A362528 A137019 A122929
KEYWORD
nonn
AUTHOR
R. H. Hardin May 27 2012
STATUS
approved

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Last modified May 24 12:49 EDT 2024. Contains 372773 sequences. (Running on oeis4.)