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Numbers that are congruent to {2, 3, 5} mod 8.
1

%I #21 Sep 08 2022 08:44:57

%S 2,3,5,10,11,13,18,19,21,26,27,29,34,35,37,42,43,45,50,51,53,58,59,61,

%T 66,67,69,74,75,77,82,83,85,90,91,93,98,99,101,106,107,109,114,115,

%U 117,122,123,125,130,131,133,138,139,141,146,147,149,154,155,157

%N Numbers that are congruent to {2, 3, 5} mod 8.

%H G. C. Greubel, <a href="/A047604/b047604.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1).

%F From _Chai Wah Wu_, May 29 2016: (Start)

%F a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.

%F G.f.: x*(x + 1)*(3*x^2 - x + 2)/((x - 1)^2*(x^2 + x + 1)). (End)

%F From _Wesley Ivan Hurt_, Jun 10 2016: (Start)

%F a(n) = 8*n/3-2-cos(2*n*Pi/3)+5*sin(2*n*Pi/3)/(3*sqrt(3)).

%F a(3k) = 8k-3, a(3k-1) = 8k-5, a(3k-2) = 8k-6. (End)

%p A047604:=n->8*n/3-2-cos(2*n*Pi/3)+5*sin(2*n*Pi/3)/(3*sqrt(3)): seq(A047604(n), n=1..100); # _Wesley Ivan Hurt_, Jun 10 2016

%t Flatten[#+{2,3,5}&/@(8*Range[0,20])] (* _Harvey P. Dale_, Oct 17 2013 *)

%t LinearRecurrence[{1, 0, 1, -1}, {2, 3, 5, 10}, 50] (* _G. C. Greubel_, May 29 2016 *)

%o (Magma) [n : n in [0..150] | n mod 8 in [2, 3, 5]]; // _Wesley Ivan Hurt_, May 29 2016

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_