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A272958 T(n,k)=Number of nXk 0..1 arrays with exactly n+k-2 having value 1 and no three 1s forming an isosceles right triangle. 8
1, 2, 2, 3, 6, 3, 4, 10, 10, 4, 5, 21, 24, 21, 5, 6, 34, 24, 24, 34, 6, 7, 62, 107, 60, 107, 62, 7, 8, 100, 236, 210, 210, 236, 100, 8, 9, 171, 499, 637, 768, 637, 499, 171, 9, 10, 276, 1228, 1840, 1898, 1898, 1840, 1228, 276, 10, 11, 458, 2753, 5792, 8211, 7468, 8211, 5792 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Table starts

.1...2....3.....4......5......6.......7.......8.......9......10.......11

.2...6...10....21.....34.....62.....100.....171.....276.....458......740

.3..10...24....24....107....236.....499....1228....2753....6292....14751

.4..21...24....60....210....637....1840....5792...18556...54034...160246

.5..34..107...210....768...1898....8211...37402..192579..635086..2366644

.6..62..236...637...1898...7468...26052..138476..831738.4677062.23090612

.7.100..499..1840...8211..26052..131056..648178.4336294

.8.171.1228..5792..37402.138476..648178.4614732

.9.276.2753.18556.192579.831738.4336294

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..126

FORMULA

Empirical for column k:

k=1: a(n) = 2*a(n-1) -a(n-2)

k=2: a(n) = a(n-1) +3*a(n-2) -2*a(n-3) -3*a(n-4) +a(n-5) +a(n-6)

k=3: [order 72]

EXAMPLE

Some solutions for n=5 k=4

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

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

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

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

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

CROSSREFS

Sequence in context: A128228 A190098 A272973 * A290632 A291543 A296320

Adjacent sequences:  A272955 A272956 A272957 * A272959 A272960 A272961

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin, May 11 2016

STATUS

approved

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Last modified July 23 19:33 EDT 2019. Contains 325263 sequences. (Running on oeis4.)