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 A145053 One-third of the number of n X n nonnegative integer arrays with every 3 X 3 subblock summing to 2. 0
 15, 71, 175, 327, 987, 2079, 3603, 9831, 19947, 33951, 89787, 180615 (list; graph; refs; listen; history; text; internal format)
 OFFSET 3,1 COMMENTS Second differences of (a(3k), a(3k + 1), a(3k + 1)) and (a(3k + 1), a(3k + 2), a(3k + 3)) appear to be 48 * 9^(k - 1). Based on this conjecture, we would have a(15) =  306435. - David A. Corneth, Apr 15 2015 LINKS CROSSREFS Sequence in context: A000475 A253476 A308596 * A168298 A126274 A241234 Adjacent sequences:  A145050 A145051 A145052 * A145054 A145055 A145056 KEYWORD nonn,more AUTHOR R. H. Hardin, Sep 30 2008 STATUS approved

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Last modified July 28 23:26 EDT 2021. Contains 346340 sequences. (Running on oeis4.)