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A125201
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8*n^2 - 7*n + 1.
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1
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2, 19, 52, 101, 166, 247, 344, 457, 586, 731, 892, 1069, 1262, 1471, 1696, 1937, 2194, 2467, 2756, 3061, 3382, 3719, 4072, 4441, 4826, 5227, 5644, 6077, 6526, 6991, 7472, 7969, 8482, 9011, 9556, 10117, 10694, 11287, 11896, 12521, 13162, 13819, 14492
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Central terms of the triangle in A125199.
Sequence found by reading the line from 2, in the direction 2, 19,..., in the square spiral whose vertices are the triangular numbers A000217. - Omar E. Pol, Sep 05 2011
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LINKS
| Index entries for sequences related to linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = 1 + A051870(n). - Omar E. Pol, Sep 05 2011
Contribution from Arkadiusz Wesolowski, Dec 25 2011: (Start)
a(1) = 2, a(n) = a(n-1) + 16*n - 15.
a(n) = 2*a(n-1) - a(n-2) + 16 with a(1) = 2 and a(2) = 19.
G.f.: (1 - x + 16*x^2)/(1 - x)^3, if the offset is 0. (End)
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PROG
| (MAGMA) [8*n^2-7*n+1:n in [1..40]]; [From Vincenzo Librandi, Dec 27 2010]
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CROSSREFS
| Sequence in context: A141067 A031911 A136685 * A140544 A204219 A042149
Adjacent sequences: A125198 A125199 A125200 * A125202 A125203 A125204
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KEYWORD
| nonn,easy
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 24 2006
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