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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
OFFSET
1,1
Row 3 of A202864.
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: A048373 A066563 A374085 * A360786 A070808 A229474
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 25 2011
STATUS
approved

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Last modified September 20 00:39 EDT 2024. Contains 376015 sequences. (Running on oeis4.)