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0, 20, 80, 180, 320, 500, 720, 980, 1280, 1620, 2000, 2420, 2880, 3380, 3920, 4500, 5120, 5780, 6480, 7220, 8000, 8820, 9680, 10580, 11520, 12500, 13520, 14580, 15680, 16820, 18000, 19220, 20480, 21780, 23120, 24500, 25920, 27380, 28880, 30420, 32000
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OFFSET
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0,2
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COMMENTS
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Sequence found by reading the line from 0, in the direction 0, 20,..., in the square spiral whose vertices are the generalized dodecagonal numbers A195162. Semi-axis opposite to A195317 in the same spiral.
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..10000
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FORMULA
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a(n) = 20*A000290(n) = 10*A001105(n) = 5*A016742(n) = 4*A033429(n) = 2*A033583(n).
a(0)=0, a(1)=20, a(2)=80, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Jan 18 2013
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MATHEMATICA
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20Range[0, 40]^2 (* or *) LinearRecurrence[{3, -3, 1}, {0, 20, 80}, 50] (* Harvey P. Dale, Jan 18 2013 *)
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PROG
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(MAGMA) [20*n^2:n in [0..40]]; // Vincenzo Librandi, Sep 20 2011
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CROSSREFS
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Bisection of A195148.
Cf. A033581, A139098, A033583, A135453, A144555, A016802, A195321, A195323.
Sequence in context: A083127 A211613 A002609 * A200424 A211463 A041776
Adjacent sequences: A195319 A195320 A195321 * A195323 A195324 A195325
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KEYWORD
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nonn,easy
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AUTHOR
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Omar E. Pol, Sep 16 2011
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STATUS
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approved
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