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Search: id:A033951
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| A033951 |
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Write 1,2,... in clockwise spiral; sequence gives numbers on positive x axis. |
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+0
25
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| 1, 8, 23, 46, 77, 116, 163, 218, 281, 352, 431, 518, 613, 716, 827, 946, 1073, 1208, 1351, 1502, 1661, 1828, 2003, 2186, 2377, 2576, 2783, 2998, 3221, 3452, 3691, 3938, 4193, 4456, 4727, 5006, 5293, 5588, 5891, 6202, 6521, 6848, 7183, 7526, 7877, 8236
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n) = 4n^2+3n+1.
G.f.: (1+5x+2x^2)/(1-x)^3.
Equals A132774 * [1, 2, 3,...]; = binomial transform of [1, 7, 8, 0, 0, 0,...]. - Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 28 2007
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EXAMPLE
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... 16 5 6 7 22 ...
... 15 4 1 8 23 ...
... 14 3 2 9 24 ...
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PROGRAM
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(PARI) a(n)=4*n^2+3*n+1
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CROSSREFS
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Sequences from spirals: A001107, A002939, A007742, A033951, A033952, A033953, A033954, A033989, A033990, A033991, A002943, A033996, A033988.
A014848(2n+1)=a(n).
Cf. A132774.
Sequence in context: A047719 A114381 A139433 this_sequence A027054 A048467 A002765
Adjacent sequences: A033948 A033949 A033950 this_sequence A033952 A033953 A033954
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KEYWORD
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nonn,easy,nice
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AUTHOR
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Olivier Gorin (gorin(AT)roazhon.inra.fr)
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EXTENSIONS
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Extended (with formula) by Erich Friedman (erich.friedman(AT)stetson.edu).
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