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Numbers that are congruent to {0, 1, 3, 4, 5} mod 6.
3

%I #27 Dec 17 2021 08:24:43

%S 0,1,3,4,5,6,7,9,10,11,12,13,15,16,17,18,19,21,22,23,24,25,27,28,29,

%T 30,31,33,34,35,36,37,39,40,41,42,43,45,46,47,48,49,51,52,53,54,55,57,

%U 58,59,60,61,63,64,65,66,67,69,70,71,72,73,75,76,77,78,79

%N Numbers that are congruent to {0, 1, 3, 4, 5} mod 6.

%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,1,-1).

%F a(n) = floor((6n-3)/5). - _Gary Detlefs_, Mar 07 2010

%F G.f.: x^2*(1+x)*(x^3+x+1) / ( (x^4+x^3+x^2+x+1)*(x-1)^2 ). - _R. J. Mathar_, Oct 08 2011

%F Sum_{n>=2} (-1)^n/a(n) = log(2+sqrt(3))/sqrt(3) - (3-2*sqrt(3))*Pi/36. - _Amiram Eldar_, Dec 17 2021

%p seq(floor((6*n-3)/5), n= 1..70); # _Gary Detlefs_, Mar 07 2010

%t Flatten[#+{0,1,3,4,5}&/@(6Range[0,12])] (* _Harvey P. Dale_, Apr 21 2011 *)

%Y Cf. A047263.

%K nonn

%O 1,3

%A _N. J. A. Sloane_