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A223391 T(n,k)=Number of (n+2)Xk 0..2 arrays with all rows having a nonnegative second derivative, and all columns having a positive second derivative in a quadratic least squares fit, with one and two element arrays taken as having a zero second derivative 6
11, 121, 31, 388, 961, 105, 4794, 5450, 11025, 342, 40416, 188958, 120738, 116964, 1044, 375698, 4182458, 14855514, 2326103, 1089936, 3159, 4128762, 101698908, 1030363654, 993542957, 40102656, 9979281, 9735, 41424210, 2972878486 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Table starts

....11.......121.........388..........4794..........40416.........375698

....31.......961........5450........188958........4182458......101698908

...105.....11025......120738......14855514.....1030363654....80122222262

...342....116964.....2326103.....993542957...208801521397.49244499538437

..1044...1089936....40102656...53115687500.31140652265964

..3159...9979281...663777212.2791742360102

..9735..94770225.11304765020

.28302.801003204

.87129

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..47

EXAMPLE

Some solutions for n=1 k=4

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

..1..0..0..0....1..0..0..0....1..0..0..0....1..1..0..0....1..0..0..1

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

CROSSREFS

Sequence in context: A081122 A004190 A089707 * A084969 A045592 A045595

Adjacent sequences:  A223388 A223389 A223390 * A223392 A223393 A223394

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Mar 19 2013

STATUS

approved

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Last modified April 20 14:27 EDT 2019. Contains 322310 sequences. (Running on oeis4.)