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 A081284 An interleaved sequence of pyramidal and polygonal numbers. 4
 0, 1, 1, 6, 7, 22, 27, 62, 77, 147, 182, 308, 378, 588, 714, 1044, 1254, 1749, 2079, 2794, 3289, 4290, 5005, 6370, 7371, 9191, 10556, 12936, 14756, 17816, 20196, 24072, 27132, 31977, 35853, 41838, 46683, 53998, 59983, 68838, 76153, 86779, 95634 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (2,3,-8,-2,12,-2,-8,3,2,-1). FORMULA G.f.: x*(1+x^3)/((1-x)*(1-x^2)^5). a(2*n) = A005585(n); a(2*n+1) = A081282(n+1). G.f.: (x*(x^2-x+1))/((x+1)^4*(x-1)^6). - Maksym Voznyy (voznyy(AT)mail.ru), Jul 28 2009 a(n) = (2*n+1-(-1)^n)*(2*n+5-(-1)^n)*(2*n+9-(-1)^n)*(2*n^2+15*n+51+3*(n-5)*(-1)^n)/30720. - Luce ETIENNE, Mar 13 2015 MATHEMATICA CoefficientList[Series[x (1 + x^3) / ((1 - x) (1 - x^2)^5), {x, 0, 50}], x] (* Vincenzo Librandi, Aug 07 2013 *) CROSSREFS Cf. A081283, A081282. Sequence in context: A062369 A048062 A295729 * A185509 A099572 A288705 Adjacent sequences:  A081281 A081282 A081283 * A081285 A081286 A081287 KEYWORD easy,nonn AUTHOR Paul Barry, Mar 17 2003 STATUS approved

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Last modified April 20 02:46 EDT 2019. Contains 322291 sequences. (Running on oeis4.)