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A008642
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Quarter-squares repeated.
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2
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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; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| The area of the largest rectangle whose perimeter is not greater than n. - Dmitry Kamenetsky, Aug 30 2006
Also number of partitions of n into parts 1, 2 or 4. [Reinhard Zumkeller, Aug 12 2011]
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REFERENCES
| 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
| 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 i = sqrt(-1).
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CROSSREFS
| Cf. A002620.
Sequence in context: A052928 A137501 A005186 * A001364 A029010 A060027
Adjacent sequences: A008639 A008640 A008641 * A008643 A008644 A008645
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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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