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A251346 Number of (n+1)X(3+1) 0..2 arrays with every 2X2 subblock summing to 3 4 or 5 1
1899, 50831, 1401453, 39019417, 1089569635, 30455338423, 851555497489, 23812875899033, 665928597808379, 18622994447540275, 520803020853242453, 14564589345979384965, 407308308989838130599, 11390647061404844346667 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A251351

LINKS

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

Robert Israel, Maple-assisted proof of formula

FORMULA

Empirical: a(n) = 39*a(n-1) -230*a(n-2) -3185*a(n-3) +26461*a(n-4) +58000*a(n-5) -743602*a(n-6) +446832*a(n-7) +5371663*a(n-8) -6391130*a(n-9) -15263203*a(n-10) +20886926*a(n-11) +20718664*a(n-12) -28063985*a(n-13) -14001799*a(n-14) +16500897*a(n-15) +4013131*a(n-16) -3984174*a(n-17) -318712*a(n-18) +318720*a(n-19) -4480*a(n-20) -4608*a(n-21).

Empirical formula confirmed: see link. - Robert Israel, Aug 05 2019

EXAMPLE

Some solutions for n=2

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

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

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

CROSSREFS

Sequence in context: A221504 A157760 A204479 * A078862 A190652 A177137

Adjacent sequences:  A251343 A251344 A251345 * A251347 A251348 A251349

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 01 2014

STATUS

approved

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Last modified January 15 09:30 EST 2021. Contains 340187 sequences. (Running on oeis4.)