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 A223639 Number of n X 3 0..1 arrays with rows, columns, diagonals and antidiagonals unimodal. 1
 7, 49, 218, 726, 2014, 4904, 10797, 21917, 41601, 74635, 127636, 209480, 331776, 509386, 760991, 1109703, 1583723, 2217045, 3050206, 4131082, 5515730, 7269276, 9466849, 12194561, 15550533, 19645967, 24606264, 30572188, 37701076, 46168094 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A223644. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = (23/360)*n^6 - (3/40)*n^5 + (31/18)*n^4 + (5/8)*n^3 + (1517/360)*n^2 - (51/20)*n + 3. Conjectures from Colin Barker, Aug 22 2018: (Start) G.f.: x*(7 + 22*x^2 - 16*x^3 + 40*x^4 - 10*x^5 + 3*x^6) / (1 - x)^7. a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n>7. (End) EXAMPLE Some solutions for n=4: ..0..1..1....1..1..0....0..0..0....0..1..0....0..1..1....0..1..0....0..0..1 ..0..1..1....1..1..0....1..1..0....1..1..0....1..1..0....1..1..0....0..0..1 ..1..1..0....1..1..0....1..1..0....0..1..1....0..0..0....1..1..0....0..1..1 ..1..0..0....0..0..1....0..0..1....0..0..1....0..0..0....1..0..0....0..1..1 CROSSREFS Cf. A223644. Sequence in context: A206866 A206872 A133047 * A188689 A188852 A188845 Adjacent sequences:  A223636 A223637 A223638 * A223640 A223641 A223642 KEYWORD nonn AUTHOR R. H. Hardin, Mar 24 2013 STATUS approved

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Last modified November 30 17:12 EST 2021. Contains 349424 sequences. (Running on oeis4.)