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A080860
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10*n^2 + 5*n + 1.
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1
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1, 16, 51, 106, 181, 276, 391, 526, 681, 856, 1051, 1266, 1501, 1756, 2031, 2326, 2641, 2976, 3331, 3706, 4101, 4516, 4951, 5406, 5881, 6376, 6891, 7426, 7981, 8556, 9151, 9766, 10401, 11056, 11731, 12426, 13141, 13876, 14631, 15406, 16201, 17016, 17851
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OFFSET
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0,2
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COMMENTS
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The old definition of this sequence was "Generalized polygonal numbers".
Sequence found by reading the line from 1, in the direction 1, 16,..., in the square spiral whose vertices are the generalized heptagonal numbers A085787. - Omar E. Pol, Sep 10 2011
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LINKS
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FORMULA
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a(n) = C(5,0) + C(5,1)*n + C(5,2)*n^2.
G.f. (C(4,0) + (C(6,2)-2)*x + C(4,2)*x^2)/(1-x)^3 = (1+13*x+6*x^2)/(1-x)^3
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MATHEMATICA
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Table[10n^2+5n+1, {n, 0, 50}] (* or *) LinearRecurrence[{3, -3, 1}, {1, 16, 51}, 50] (* Harvey P. Dale, Aug 05 2014 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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Definition replaced with the closed form by Bruno Berselli, Jan 16 2013
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STATUS
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approved
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