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A202865 Number of 3 X 3 0..n arrays with row and column sums one greater than the previous row and column. 1
2, 42, 228, 776, 2046, 4578, 9128, 16704, 28602, 46442, 72204, 108264, 157430, 222978, 308688, 418880, 558450, 732906, 948404, 1211784, 1530606, 1913186, 2368632, 2906880, 3538730, 4275882, 5130972, 6117608, 7250406, 8545026 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A202864.

LINKS

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

FORMULA

Empirical: a(n) = (3/10)*n^5 + (3/2)*n^4 + (3/2)*n^3 - (1/2)*n^2 - (4/5)*n.

Conjectures from Colin Barker, Jun 02 2018: (Start)

G.f.: 2*x*(1 + 15*x + 3*x^2 - x^3) / (1 - x)^6.

a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n>6.

(End)

EXAMPLE

Some solutions for n=7:

  6 5 2   2 5 4   1 7 4   4 4 2   2 2 1   6 3 0   2 6 2

  6 2 6   3 5 4   5 1 7   1 4 6   0 0 6   2 2 6   3 4 4

  1 7 7   6 2 5   6 5 3   5 3 4   3 4 0   1 5 5   5 1 6

CROSSREFS

Cf. A202864.

Sequence in context: A291173 A048373 A066563 * A070808 A229474 A157056

Adjacent sequences:  A202862 A202863 A202864 * A202866 A202867 A202868

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 25 2011

STATUS

approved

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Last modified September 22 23:50 EDT 2021. Contains 347609 sequences. (Running on oeis4.)