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 A250891 Number of (n+1) X (1+1) 0..2 arrays with nondecreasing x(i,j)-x(i,j-1) in the i direction and nondecreasing absolute value of x(i,j)-x(i-1,j) in the j direction. 2
 37, 125, 413, 1333, 4213, 13111, 40357, 123271, 374509, 1133503, 3421621, 10309399, 31021885, 93262255, 280198405, 841455367, 2526160141, 7582215967, 22754413909, 68279363575, 204871514077, 614683748239, 1844194375333, 5532878824423 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 1 of A250898. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 8*a(n-1) - 23*a(n-2) + 28*a(n-3) - 12*a(n-4) for n > 6. Empirical g.f.: x*(37 - 171*x + 264*x^2 - 132*x^3 - 8*x^4 + 2*x^5) / ((1 - x)*(1 - 2*x)^2*(1 - 3*x)). - Colin Barker, Mar 19 2018 EXAMPLE Some solutions for n=4: 2 1 1 0 1 0 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 2 2 1 2 1 1 1 1 1 0 0 2 1 0 0 1 1 1 1 2 2 2 1 1 0 0 0 1 1 1 1 1 2 0 0 0 0 0 0 0 0 1 0 1 0 2 2 1 1 0 0 1 2 2 2 1 1 2 2 1 1 2 2 2 2 0 0 0 0 0 1 0 1 1 1 1 1 2 2 CROSSREFS Cf. A250898. Sequence in context: A044288 A044669 A048510 * A250898 A165811 A142331 Adjacent sequences: A250888 A250889 A250890 * A250892 A250893 A250894 KEYWORD nonn AUTHOR R. H. Hardin, Nov 28 2014 STATUS approved

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Last modified September 21 14:24 EDT 2023. Contains 365502 sequences. (Running on oeis4.)