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A096376
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a(n) = n + (n-1)^2 + (n+1)^2.
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11
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2, 5, 12, 23, 38, 57, 80, 107, 138, 173, 212, 255, 302, 353, 408, 467, 530, 597, 668, 743, 822, 905, 992, 1083, 1178, 1277, 1380, 1487, 1598, 1713, 1832, 1955, 2082, 2213, 2348, 2487, 2630, 2777, 2928, 3083, 3242, 3405, 3572, 3743, 3918, 4097, 4280, 4467, 4658
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OFFSET
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0,1
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COMMENTS
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Numbers represented as 212 in number base n including binary with digits larger than 1: 212_2 = 12 and ternary 212_3 = 23. - Ron Knott, Nov 14 2017
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LINKS
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FORMULA
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a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
G.f.: (2 - x + 3*x^2)/(1-x)^3. (End)
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EXAMPLE
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1 + 0 + 4 = 5, 2 + 1 + 9 = 12, 3 + 4 + 16 = 23, ...
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MAPLE
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MATHEMATICA
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LinearRecurrence[{3, -3, 1}, {2, 5, 12}, 50] (* Harvey P. Dale, Mar 15 2015 *)
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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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