

A200887


Number of 0..n arrays x(0..3) of 4 elements without any interior element greater than both neighbors


1



12, 51, 144, 325, 636, 1127, 1856, 2889, 4300, 6171, 8592, 11661, 15484, 20175, 25856, 32657, 40716, 50179, 61200, 73941, 88572, 105271, 124224, 145625, 169676, 196587, 226576, 259869, 296700, 337311, 381952, 430881, 484364, 542675, 606096, 674917
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OFFSET

1,1


COMMENTS

Row 2 of A200886


LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210


FORMULA

Empirical: a(n) = (1/3)*n^4 + (7/3)*n^3 + (14/3)*n^2 + (11/3)*n + 1


EXAMPLE

Some solutions for n=3
..3....1....0....0....3....1....3....1....2....2....0....1....3....1....3....2
..2....1....1....0....1....1....1....0....2....3....3....0....3....3....3....0
..1....3....1....2....2....0....3....1....2....3....3....0....2....3....1....2
..1....3....0....3....3....1....3....2....2....3....2....2....2....0....2....2


CROSSREFS

Sequence in context: A051797 A145886 A166776 * A236770 A115680 A231298
Adjacent sequences: A200884 A200885 A200886 * A200888 A200889 A200890


KEYWORD

nonn


AUTHOR

R. H. Hardin Nov 23 2011


STATUS

approved



