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A139609
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a(n) = 36*n + 9.
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4
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9, 45, 81, 117, 153, 189, 225, 261, 297, 333, 369, 405, 441, 477, 513, 549, 585, 621, 657, 693, 729, 765, 801, 837, 873, 909, 945, 981, 1017, 1053, 1089, 1125, 1161, 1197, 1233, 1269, 1305, 1341, 1377, 1413, 1449, 1485, 1521, 1557, 1593, 1629, 1665, 1701
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OFFSET
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0,1
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COMMENTS
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Numbers of the 9th column of positive numbers in the square array of nonnegative and polygonal numbers A139600.
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LINKS
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FORMULA
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E.g.f.: 9*exp(x)*(1 + 4*x).
a(n) = 2*a(n-1) - a(n-2) for n >= 2.
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MATHEMATICA
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36*Range[0, 50]+9 (* or *) LinearRecurrence[{2, -1}, {9, 45}, 50] (* Harvey P. Dale, Jan 04 2018 *)
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PROG
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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