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 A026068 (d(n)-r(n))/5, where d = A026066 and r is the periodic sequence with fundamental period (0,3,1,0,1). 1
 21, 33, 49, 68, 90, 116, 145, 179, 217, 259, 306, 357, 414, 476, 543, 616, 694, 779, 870, 967, 1071, 1181, 1299, 1424, 1556, 1696, 1843, 1999, 2163, 2335, 2516, 2705, 2904, 3112, 3329, 3556, 3792, 4039, 4296, 4563, 4841, 5129, 5429, 5740, 6062, 6396, 6741 (list; graph; refs; listen; history; text; internal format)
 OFFSET 7,1 LINKS Index entries for linear recurrences with constant coefficients, signature (3, -3, 1, 0, 1, -3, 3, -1). FORMULA a(n)=(n + 7)*(n^2 + 35*n + 90)/30 - 1/5*(1 + ( - 1/2 + 3/10*5^(1/2))*cos(2*n*Pi/5) + (1/5*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/10*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(2*n*Pi/5) + ( - 1/2 - 3/10*5^(1/2))*cos(4*n*Pi/5) + ( - 1/10*2^(1/2)*(5 + 5^(1/2))^(1/2) + 1/5*2^(1/2)*(5 - 5^(1/2))^(1/2))*sin(4*n*Pi/5)) [From Richard Choulet, Dec 14 2008] a(n)= 3*a(n-1) -3*a(n-2) +a(n-3) +a(n-5) -3*a(n-6) +3*a(n-7) -a(n-8). G.f.: -x^7*(-21+30*x-13*x^2+x^3+20*x^5-29*x^6+11*x^7)/( (x^4+x^3+x^2+x+1) * (x-1)^4). [From R. J. Mathar, Oct 05 2009] MATHEMATICA LinearRecurrence[{3, -3, 1, 0, 1, -3, 3, -1}, {21, 33, 49, 68, 90, 116, 145, 179}, 60] (* Harvey P. Dale, Sep 10 2014 *) CROSSREFS A152892 [From Richard Choulet, Dec 14 2008] Sequence in context: A119973 A279229 A141249 * A217263 A330441 A176945 Adjacent sequences:  A026065 A026066 A026067 * A026069 A026070 A026071 KEYWORD nonn AUTHOR EXTENSIONS Corrected by T. D. Noe, Dec 11 2006 STATUS approved

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Last modified January 27 04:57 EST 2020. Contains 331291 sequences. (Running on oeis4.)