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Search: id:A008642
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| A008642 |
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Quarter-squares repeated. |
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+0
3
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| 1, 1, 2, 2, 4, 4, 6, 6, 9, 9, 12, 12, 16, 16, 20, 20, 25, 25, 30, 30, 36, 36, 42, 42, 49, 49, 56, 56, 64, 64, 72, 72, 81, 81, 90, 90, 100, 100, 110, 110, 121, 121, 132, 132, 144, 144, 156, 156, 169, 169, 182
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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The area of the largest rectangle whose perimeter is not greater than n. - Dmitry Kamenetsky (Dmitry.Kamenetsky(AT)rsise.anu.edu.au), Aug 30 2006
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REFERENCES
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D. J. Benson, Polynomial Invariants of Finite Groups, Cambridge, 1993, p. 105.
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 112, D(n).
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FORMULA
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G.f.: 1/((1-x)*(1-x^2)*(1-x^4)).
a(n)= ((21+14*n+2*n^2)+((-1)^n)*(7+2*n))/32 +(I^n)*((1+(-1)^n)/2-I*(1-(-1)^n)/2)/8 with the complex unit I.
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CROSSREFS
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Cf. A002620.
Sequence in context: A052928 A137501 A005186 this_sequence A001364 A029010 A060027
Adjacent sequences: A008639 A008640 A008641 this_sequence A008643 A008644 A008645
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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