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A185918
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12n^2 - 2n - 1.
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1
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-1, 9, 43, 101, 183, 289, 419, 573, 751, 953, 1179, 1429, 1703, 2001, 2323, 2669, 3039, 3433, 3851, 4293, 4759, 5249, 5763, 6301, 6863, 7449, 8059, 8693, 9351, 10033, 10739, 11469, 12223, 13001, 13803, 14629, 15479, 16353, 17251, 18173, 19119, 20089, 21083, 22101, 23143, 24209
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OFFSET
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0,2
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COMMENTS
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The second quadrisection of A184005(n-1) is A179741(n).
The first quadrisection of A184005(n-1) is a(n).
Sequence found by reading the line from -1, in the direction -1, 9,..., in the square spiral whose vertices are -1 together with the generalized octagonal numbers A001082. - Omar E. Pol, Jul 18 2012
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LINKS
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Table of n, a(n) for n=0..45.
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,1).
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FORMULA
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a(n)=A184005(4*n-1). - corrected by R. J. Mathar, Aug 24 2011
a(n)=a(n-1)+24*n-14.
a(n)=2*a(n-1)-a(n)+24.
a(n)=3*a(n-1)-3*a(n-2)+a(n-3).
G.f. -(1+x)*(13*x-1) / (x-1)^3 . - R. J. Mathar, Aug 24 2011
a(n) = A154106(n-1) - 2, n >= 1. - Omar E. Pol, Jul 19 2012
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MATHEMATICA
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Table[12n^2-2n-1, {n, 0, 50}] (* or *) LinearRecurrence[{3, -3, 1}, {-1, 9, 43}, 50] Harvey P. Dale, May 20 2012
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PROG
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(MAGMA) [-1-2*n+12*n^2: n in [0..80] ]; [From Vincenzo Librandi, Feb 09 2011]
(PARI) a(n)=12*n^2-2*n-1 \\ Charles R Greathouse IV, Dec 21 2011
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CROSSREFS
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Sequence in context: A221425 A007227 A195975 * A116015 A181945 A220676
Adjacent sequences: A185915 A185916 A185917 * A185919 A185920 A185921
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KEYWORD
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sign,easy,changed
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AUTHOR
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Paul Curtz, Feb 08 2011
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EXTENSIONS
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More terms from Vincenzo Librandi, Feb 09 2011
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STATUS
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approved
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