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A014634
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(2n+1)*(4n+1).
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18
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1, 15, 45, 91, 153, 231, 325, 435, 561, 703, 861, 1035, 1225, 1431, 1653, 1891, 2145, 2415, 2701, 3003, 3321, 3655, 4005, 4371, 4753, 5151, 5565, 5995, 6441, 6903, 7381, 7875, 8385, 8911, 9453, 10011
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Odd hexagonal numbers. Bisection of A000384. - Omar E. Pol (info(AT)polprimos.com), Apr 06 2008
A014634 * 2 = A157870. A157870 / 2 = A014634. [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 10 2009]
Sequence found by reading the line from 1, in the direction 1, 15,..., in the square spiral whose vertices are the triangular numbers A000217. - Omar E. Pol, Sep 03 2011
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
| a(n) = a(n-1)+16*n-2 (with a(0)=1). [From Vincenzo Librandi, Nov 20 2010]
G.f.: (1+12*x+3*x^2)/(1-x)^3. [Colin Barker, Jan 08 2012]
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MATHEMATICA
| lst={}; Do[a=(2*n+1)*(4*n+1); AppendTo[lst, a], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 10 2009]
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CROSSREFS
| Cf. A000384.
Sequence in context: A033849 A194715 A060536 * A126228 A072251 A002756
Adjacent sequences: A014631 A014632 A014633 * A014635 A014636 A014637
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KEYWORD
| nonn,easy
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AUTHOR
| Mohammad K. Azarian (ma3(AT)evansville.edu), N. J. A. Sloane (njas(AT)research.att.com).
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