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A026019
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C(3n,n) - C(3n,n-3).
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0
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1, 3, 15, 83, 483, 2898, 17748, 110295, 692967, 4390815, 28009215, 179652564, 1157534420, 7486680048, 48579667704, 316107403839, 2061920664351, 13478362911825, 88272020923485, 579081767982795, 3804622827123195
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| G.f.: (1-2*g)*(g^2-g+1)/((3*g-1)*(g-1)^3) where g*(1-g)^2 = x. - Mark van Hoeij, Nov 09 2011
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CROSSREFS
| a(n) = T(3n, n), where T is the array defined in A026009.
Sequence in context: A203507 A192662 A052451 * A118356 A074552 A193658
Adjacent sequences: A026016 A026017 A026018 * A026020 A026021 A026022
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KEYWORD
| nonn,easy
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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EXTENSIONS
| More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 17 2005
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