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A054569
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4*n^2 - 6*n + 3.
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18
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1, 7, 21, 43, 73, 111, 157, 211, 273, 343, 421, 507, 601, 703, 813, 931, 1057, 1191, 1333, 1483, 1641, 1807, 1981, 2163, 2353, 2551, 2757, 2971, 3193, 3423, 3661, 3907, 4161, 4423, 4693, 4971, 5257, 5551, 5853, 6163, 6481, 6807, 7141, 7483, 7833, 8191
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Move in 1-7 direction in a spiral organized like A068225 etc.
Third row of A082039. - Paul Barry (pbarry(AT)wit.ie), Apr 02 2003
Inverse binomial transform of A036826. - Paul Barry (pbarry(AT)wit.ie), Jun 11 2003
Equals the ‘middle sequence’ T(2*n,n) of the Connell sequence A001614 as a triangle. [From Johannes W. Meijer, May 20 2011]
Ulam's spiral (SW spoke). - Robert G. Wilson v, Oct 31 2011
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FORMULA
| a(n+1)=4*n^2+2*n+1. - Paul Barry (pbarry(AT)wit.ie), Apr 02 2003
a(n)=4*n^2-6*n+3-3*0^n (with leading zero). - Paul Barry (pbarry(AT)wit.ie), Jun 11 2003
Binomial transform of [1, 6, 8, 0, 0, 0,...]. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Dec 28 2007
a(n)=8*n+a(n-1)-10 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 07 2010]
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EXAMPLE
| For n=2, a(2)=8*2+1-10=7; n=3, a(3)=8*3+7-10=21; n=4, a(4)=8*4+21-10=43 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 07 2010]
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MATHEMATICA
| f[n_] := 4*n^2-6*n+3; Array[f, 40] [From Vladimir Orlovsky, Sep 02 2008]
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CROSSREFS
| Cf. A054568, A068225, A054552, A054554, A054556, A054567, A033951.
Sequence in context: A162818 A024966 A022602 * A077354 A146411 A127736
Adjacent sequences: A054566 A054567 A054568 * A054570 A054571 A054572
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KEYWORD
| easy,nonn
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AUTHOR
| Enoch Haga, G. L. Honaker, Jr. (Enokh(AT)comcast.net), Apr 10 2000
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EXTENSIONS
| Edited by Frank Ellermann, Feb 24 2002
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