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A252832 Number of n X 4 nonnegative integer arrays with upper left 0 and every value within 2 of its king move distance from the upper left and every value increasing by 0 or 1 with every step right, diagonally se or down. 1
7, 29, 127, 493, 1474, 3365, 6211, 10017, 14783, 20509, 27195, 34841, 43447, 53013, 63539, 75025, 87471, 100877, 115243, 130569, 146855, 164101, 182307, 201473, 221599, 242685, 264731, 287737, 311703, 336629, 362515, 389361, 417167, 445933 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 480*n^2 - 3394*n + 6449 for n>5.

Conjectures from Colin Barker, Dec 06 2018: (Start)

G.f.: x*(7 + 8*x + 61*x^2 + 192*x^3 + 347*x^4 + 295*x^5 + 45*x^6 + 5*x^7) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>8.

(End)

EXAMPLE

Some solutions for n=4:

..0..1..1..1....0..0..1..1....0..1..1..2....0..0..1..1....0..1..1..1

..0..1..1..1....1..1..1..1....0..1..1..2....0..0..1..1....1..1..2..2

..0..1..1..2....1..2..2..2....0..1..1..2....0..1..1..2....1..2..2..2

..1..1..2..2....1..2..2..3....1..1..2..2....1..1..1..2....2..2..3..3

CROSSREFS

Column 4 of A252836.

Sequence in context: A055427 A048876 A126394 * A074468 A303091 A179599

Adjacent sequences:  A252829 A252830 A252831 * A252833 A252834 A252835

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 22 2014

STATUS

approved

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Last modified November 13 17:34 EST 2019. Contains 329106 sequences. (Running on oeis4.)