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A059993
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Pinwheel numbers: 2*n^2 + 6*n + 1.
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2
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1, 9, 21, 37, 57, 81, 109, 141, 177, 217, 261, 309, 361, 417, 477, 541, 609, 681, 757, 837, 921, 1009, 1101, 1197, 1297, 1401, 1509, 1621, 1737, 1857, 1981, 2109, 2241, 2377, 2517, 2661, 2809, 2961, 3117, 3277, 3441, 3609, 3781, 3957, 4137, 4321, 4509
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| Harry J. Smith, Table of n, a(n) for n=0,...,1000
figure
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FORMULA
| a(n)=4*n+a(n-1)+4 (with a(0)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 07 2010]
G.f.: (1 + 6*x - 3*x^2)/(1 - x)^3. [Arkadiusz Wesolowski, Dec 24 2011]
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EXAMPLE
| a(1)=4*1+1+4=9; a(2)=4*2+9+4=21; a(3)=4*3+21+4=37 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 07 2010]
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MATHEMATICA
| a=-3; lst={}; Do[a+=n; AppendTo[lst, a], {n, 0, 6!, 4}]; lst...and/or... lst={}; Do[AppendTo[lst, 2*n^2+6*n+1], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Mar 01 2009]
1. Table[2*n^2 + 6*n + 1, {n, 0, 46}] (.) 2. lst = {}; Do[a = 2*n^2 + 6*n + 1; AppendTo[lst, a], {n, 0, 46}]; lst (.) [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 10 2009]
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PROG
| (PARI) { for (n=0, 1000, write("b059993.txt", n, " ", 2*n^2 + 6*n + 1); ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Jul 01 2009]
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CROSSREFS
| Sequence in context: A146069 A140673 A186294 * A036704 A107890 A110209
Adjacent sequences: A059990 A059991 A059992 * A059994 A059995 A059996
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KEYWORD
| easy,nonn
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AUTHOR
| Naohiro Nomoto (6284968128(AT)geocities.co.jp), Mar 14 2001
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