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0, 10, 36, 78, 136, 210, 300, 406, 528, 666, 820, 990, 1176, 1378, 1596, 1830, 2080, 2346, 2628, 2926, 3240, 3570, 3916, 4278, 4656, 5050, 5460, 5886, 6328, 6786, 7260, 7750, 8256, 8778, 9316, 9870, 10440
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| If Y is a fixed 3-subset of a (4n+1)-set X then a(n) is the number of (4n-1)-subsets of X intersecting Y. - Milan R. Janjic (agnus(AT)blic.net), Oct 28 2007
a(n) = A000217(4*n) = A014105(2*n). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Sep 17 2008]
Sequence found by reading the line from 0, in the direction 0, 10,..., in the square spiral whose vertices are the triangular numbers A000217. - Omar E. Pol, Sep 03 2011
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LINKS
| Milan Janjic, Two Enumerative Functions
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FORMULA
| a(n)=16*n+a(n-1)-6 (with a(0)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
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EXAMPLE
| a(1)=16*1+0-6=10; a(2)=16*2+10-6=36; a(3)=16*3+36-6=78 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 05 2010]
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MAPLE
| seq(binomial(4*n+1, 2), n=0..36); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 21 2007
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MATHEMATICA
| f[n_]:=2*n*(4*n+1); f[Range[0, 60]] (*From Vladimir Joseph Stephan Orlovsky, Feb 05 2011*)
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CROSSREFS
| Cf. A081266, A144312, A144314. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Sep 17 2008]
Sequence in context: A176575 A073613 A072517 * A118629 A050509 A118415
Adjacent sequences: A033582 A033583 A033584 * A033586 A033587 A033588
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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