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A114220
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Sum{k=0..floor(n/2), k-(k-1)*0^(n-2k)}.
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3
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1, 0, 1, 1, 2, 3, 4, 6, 7, 10, 11, 15, 16, 21, 22, 28, 29, 36, 37, 45, 46, 55, 56, 66, 67, 78, 79, 91, 92, 105, 106, 120, 121, 136, 137, 153, 154, 171, 172, 190, 191, 210, 211, 231, 232, 253, 254, 276, 277, 300, 301, 325, 326, 351, 352, 378, 379, 406, 407, 435, 436
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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COMMENTS
| Diagonal sums of A114219.
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (1,2,-2,-1,1)
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FORMULA
| G.f.: (1-x-x^2+2x^3)/((1-x)(1-x^2)^2); a(n)=a(n-1)+2a(n-2)-2a(n-3)-a(n-4)+a(n-5); a(n)=(2n^2-2n+7)/16+(9-2n)(-1)^n/16.
a(n)=A055802(n+1), n >1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 11 2008]
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MATHEMATICA
| CoefficientList[Series[(1-x-x^2+2x^3)/((1-x)(1-x^2)^2), {x, 0, 80}], x] (* From Harvey P. Dale, Mar 24 2011 *)
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CROSSREFS
| Sequence in context: A120440 A049995 A055802 * A134519 A101505 A068713
Adjacent sequences: A114217 A114218 A114219 * A114221 A114222 A114223
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Nov 18 2005
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