A252401 - OEIS

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A252401

Number of (n+2) X (2+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 2 3 4 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 2 3 4 6 or 7.

661, 442, 688, 1224, 2414, 5061, 10129, 21427, 46070, 93671, 200430, 433693, 885001, 1898578, 4117127, 8413072, 18067521, 39215676, 80182777, 172284095, 374104916, 765132570, 1644394003, 3571453244, 7305450882, 15702421450, 34107480805

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Column 2 of A252407.

LINKS

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

FORMULA

Empirical: a(n) = 16*a(n-3) -74*a(n-6) +141*a(n-9) -235*a(n-12) +206*a(n-15) -72*a(n-18) +16*a(n-21) +4*a(n-24) -a(n-27) for n>31.

EXAMPLE

Some solutions for n=4

..2..3..2..2....0..2..2..3....3..2..2..0....0..2..0..0....1..0..2..0

..3..0..1..3....3..1..3..0....2..3..2..2....3..3..0..3....0..3..3..1

..3..2..2..3....2..2..3..2....0..3..1..3....2..0..0..2....0..2..0..0

..2..3..2..2....0..2..2..3....3..2..2..3....0..2..0..0....0..0..2..0

..3..3..1..0....3..1..3..0....2..3..2..2....3..3..0..3....0..3..3..0

..3..2..2..3....2..2..3..2....3..0..1..3....2..0..1..2....0..2..0..0

CROSSREFS

Cf. A252407.

Sequence in context: A252457 A252450 A252449 * A171394 A243886 A145750

Adjacent sequences: A252398 A252399 A252400 * A252402 A252403 A252404

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 17 2014

STATUS

approved