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A253328 Number of (3+1)X(n+1) 0..1 arrays with every 2X2 subblock sum nondecreasing horizontally, vertically and antidiagonally ne-to-sw 1
121, 377, 1217, 3787, 11506, 31999, 86922, 217799, 537127, 1242718, 2846066, 6208632, 13461284, 28145490, 58668559, 119104209, 241640885, 481269481, 959688428, 1890550722, 3733605722, 7319677531, 14396259965, 28207082638 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A253326

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) +20*a(n-2) -98*a(n-3) -168*a(n-4) +1122*a(n-5) +674*a(n-6) -7970*a(n-7) -205*a(n-8) +39322*a(n-9) -13326*a(n-10) -142896*a(n-11) +86380*a(n-12) +395612*a(n-13) -325028*a(n-14) -850708*a(n-15) +867429*a(n-16) +1433880*a(n-17) -1752520*a(n-18) -1894178*a(n-19) +2759240*a(n-20) +1938970*a(n-21) -3430470*a(n-22) -1491450*a(n-23) +3380665*a(n-24) +795530*a(n-25) -2631230*a(n-26) -214060*a(n-27) +1599540*a(n-28) -65400*a(n-29) -744088*a(n-30) +104272*a(n-31) +255920*a(n-32) -56864*a(n-33) -61344*a(n-34) +17856*a(n-35) +9152*a(n-36) -3200*a(n-37) -640*a(n-38) +256*a(n-39)

EXAMPLE

Some solutions for n=4

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

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

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

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

CROSSREFS

Sequence in context: A167721 A330670 A253321 * A257035 A128608 A326710

Adjacent sequences:  A253325 A253326 A253327 * A253329 A253330 A253331

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2014

STATUS

approved

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Last modified June 25 19:25 EDT 2022. Contains 354851 sequences. (Running on oeis4.)