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A047461
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Numbers that are congruent to {1, 4} mod 8.
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2
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1, 4, 9, 12, 17, 20, 25, 28, 33, 36, 41, 44, 49, 52, 57, 60, 65, 68, 73, 76, 81, 84, 89, 92, 97, 100, 105, 108, 113, 116, 121, 124, 129, 132, 137, 140, 145, 148, 153, 156, 161, 164, 169, 172, 177, 180, 185, 188, 193, 196, 201, 204, 209, 212, 217, 220, 225, 228, 233
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Maximal number of squares that can be covered by a queen on an n X n chessboard. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 15 2008]
a(n) = A153125(n,n). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 20 2008]
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (1,1,-1).
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FORMULA
| G.f.: x(1+3x+4x^2)/((1+x)(1-x)^2). a(n)=a(n-2)+8. a(n)+a(n+1)=A004770(n). a(n+1)-a(n)=A010703(n). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 29 2008]
a(n) = 8*floor((n-1)/2) + 4 - 3*(n mod 2). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 15 2008]
a(n)=8*n-a(n-1)-11 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 06 2010]
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EXAMPLE
| For n=2, a(2)=8*2-1-11=4; n=3, a(3)=8*3-4-11=9; n=4, a(4)=8*4-9-11=12 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Aug 06 2010]
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CROSSREFS
| A017077, A017113. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 15 2008]
Sequence in context: A109424 A034019 A034018 * A190448 A089910 A177880
Adjacent sequences: A047458 A047459 A047460 * A047462 A047463 A047464
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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