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 A280904 Number of 3Xn 0..2 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards. 1
 0, 9, 646, 22568, 492490, 9426050, 162640161, 2636238543, 40818734359, 610807332682, 8899797476985, 126936297853576, 1779063560531884, 24572630681534366, 335222285940398228, 4524762545977409290 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row 3 of A280902. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 33*a(n-1) -294*a(n-2) -667*a(n-3) +16806*a(n-4) -5121*a(n-5) -389950*a(n-6) +278709*a(n-7) +5095965*a(n-8) -3346390*a(n-9) -41873331*a(n-10) +15827649*a(n-11) +225089912*a(n-12) +21687735*a(n-13) -781184967*a(n-14) -677069112*a(n-15) +1532218374*a(n-16) +3816125286*a(n-17) -205248782*a(n-18) -10810606968*a(n-19) -8772390618*a(n-20) +14265527040*a(n-21) +28972645413*a(n-22) +4449696537*a(n-23) -47676340890*a(n-24) -49006792749*a(n-25) +33750291246*a(n-26) +84325212377*a(n-27) +22629768081*a(n-28) -73666126236*a(n-29) -77116545584*a(n-30) +28481649930*a(n-31) +84486500724*a(n-32) +8922526848*a(n-33) -53642734755*a(n-34) -20170947015*a(n-35) +20632416015*a(n-36) +15610729314*a(n-37) -3175177428*a(n-38) -8006609696*a(n-39) -1561010208*a(n-40) +2779299648*a(n-41) +1314081664*a(n-42) -535991040*a(n-43) -521884416*a(n-44) -26788352*a(n-45) +145327104*a(n-46) +56180736*a(n-47) -25534464*a(n-48) -17252352*a(n-49) +688128*a(n-50) +2818048*a(n-51) +983040*a(n-52) -393216*a(n-53) -262144*a(n-54) for n>60 EXAMPLE Some solutions for n=4 ..0..1..1..1. .0..0..1..2. .0..1..1..0. .0..0..1..1. .0..1..0..0 ..0..1..2..0. .2..2..2..0. .0..0..1..0. .1..0..0..1. .1..0..1..0 ..1..0..1..1. .0..1..2..0. .0..1..1..2. .1..0..1..1. .1..2..0..0 CROSSREFS Cf. A280902. Sequence in context: A188394 A157597 A211611 * A210053 A128795 A323425 Adjacent sequences:  A280901 A280902 A280903 * A280905 A280906 A280907 KEYWORD nonn AUTHOR R. H. Hardin, Jan 10 2017 STATUS approved

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Last modified January 17 10:30 EST 2019. Contains 319218 sequences. (Running on oeis4.)