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 A214675 9*n^2 - 13*n + 5. 6
 1, 15, 47, 97, 165, 251, 355, 477, 617, 775, 951, 1145, 1357, 1587, 1835, 2101, 2385, 2687, 3007, 3345, 3701, 4075, 4467, 4877, 5305, 5751, 6215, 6697, 7197, 7715, 8251, 8805, 9377, 9967, 10575, 11201, 11845, 12507, 13187, 13885, 14601, 15335, 16087 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Central terms of triangle A214661. LINKS Index entries for linear recurrences with constant coefficients, signature (3,-3,1). FORMULA G.f.: x*(1+12*x+5*x^2)/(1-x)^3. - Bruno Berselli, Dec 10 2012 a(n) = n*A000567(n)-(n-1)*A000567(n-1). - Bruno Berselli, Dec 10 2012 PROG (Haskell) a214675 n = (9 * n - 13) * n + 5 (PARI) a(n)=9*n^2-13*n+5 \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A001106, A214661. Cf. A220083 for a list of numbers of the form n*P(s,n)-(n-1)*P(s,n-1), where P(s,n) is the n-th polygonal number with s sides. Sequence in context: A031451 A105572 A143031 * A166118 A063396 A236401 Adjacent sequences:  A214672 A214673 A214674 * A214676 A214677 A214678 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Jul 25 2012 STATUS approved

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Last modified June 25 07:53 EDT 2019. Contains 324347 sequences. (Running on oeis4.)