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 A080860 10*n^2 + 5*n + 1. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The old definition of this sequence was "Generalized polygonal numbers". Column T(n,5) of A080853. 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 LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA 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 a(n) = 20*n+a(n-1)-5 with n>0, a(0)=1. - Vincenzo Librandi, Aug 08 2010 MATHEMATICA Table[10n^2+5n+1, {n, 0, 50}] (* or *) LinearRecurrence[{3, -3, 1}, {1, 16, 51}, 50] (* Harvey P. Dale, Aug 05 2014 *) PROG (PARI) a(n)=10*n^2+5*n+1 \\ Charles R Greathouse IV, Jun 17 2017 CROSSREFS Sequence in context: A221485 A204723 A204962 * A204716 A192248 A297640 Adjacent sequences:  A080857 A080858 A080859 * A080861 A080862 A080863 KEYWORD nonn,easy AUTHOR Paul Barry, Feb 23 2003 EXTENSIONS Definition replaced with the closed form by Bruno Berselli, Jan 16 2013 STATUS approved

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Last modified August 11 09:55 EDT 2020. Contains 336423 sequences. (Running on oeis4.)