

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



LINKS



FORMULA

Empirical: a(n) = a(n1) +2*a(n2) +3*a(n3) +2*a(n4).
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



KEYWORD

nonn


AUTHOR



STATUS

approved



