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A026048 (d(n)-r(n))/5, where d = A026046 and r is the periodic sequence with fundamental period (1,0,4,0,0). 1
15, 21, 28, 39, 52, 68, 88, 111, 140, 173, 211, 255, 304, 361, 424, 494, 572, 657, 752, 855, 967, 1089, 1220, 1363, 1516, 1680, 1856, 2043, 2244, 2457, 2683, 2923, 3176, 3445, 3728, 4026, 4340, 4669, 5016, 5379, 5759, 6157, 6572, 7007, 7460, 7932, 8424, 8935, 9468, 10021, 10595, 11191 (list; graph; refs; listen; history; text; internal format)
OFFSET

6,1

LINKS

Table of n, a(n) for n=6..57.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1,0,1,-3,3,-1)

FORMULA

a(n)=(n + 6)*(n^2 + 6*n + 38)/15 - 1/5*( 1 - 2/5*5^(1/2)*cos(2*n*Pi/5) + 2/5*2^(1/2)*(5 - 5^(1/2))^(1/2)*sin(2*n*Pi/5) + 2/5*5^(1/2)*cos(4*n*Pi/5) - 2/5*2^(1/2)*(5 + 5^(1/2))^(1/2)*sin(4*n*Pi/5)) [From Richard Choulet, Dec 14 2008]

G.f. x^6*( 15-24*x+10*x^2+3*x^3-2*x^4-14*x^5+25*x^6-11*x^7 ) / ( (x^4+x^3+x^2+x+1)*(x-1)^4 ). - R. J. Mathar, Jun 22 2013

MATHEMATICA

LinearRecurrence[{3, -3, 1, 0, 1, -3, 3, -1}, {15, 21, 28, 39, 52, 68, 88, 111}, 60] (* Harvey P. Dale, Apr 01 2018 *)

CROSSREFS

A152889 [From Richard Choulet, Dec 14 2008]

Sequence in context: A082686 A102030 A168104 * A195527 A047200 A070537

Adjacent sequences:  A026045 A026046 A026047 * A026049 A026050 A026051

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified January 26 01:48 EST 2020. Contains 331270 sequences. (Running on oeis4.)