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Numbers that are congruent to {0, 2} mod 8.
13

%I #53 Jul 26 2022 05:45:39

%S 0,2,8,10,16,18,24,26,32,34,40,42,48,50,56,58,64,66,72,74,80,82,88,90,

%T 96,98,104,106,112,114,120,122,128,130,136,138,144,146,152,154,160,

%U 162,168,170,176,178,184,186,192,194,200,202,208,210,216,218,224,226,232

%N Numbers that are congruent to {0, 2} mod 8.

%H David Lovler, <a href="/A047467/b047467.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).

%F From _R. J. Mathar_, Sep 19 2008: (Start)

%F a(n) = 4*n - 5 - (-1)^n = 2*A042948(n-1).

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

%F a(n) = 8*n - a(n-1) - 14 with a(1)=0. - _Vincenzo Librandi_, Aug 06 2010

%F a(n+1) = Sum_{k>=0} A030308(n,k)*b(k) with b(0)=2 and b(k)=2^(k+2)for k > 0. - _Philippe Deléham_, Oct 17 2011

%F a(n) = floor((8/3)*floor(3*n/2)). - _Clark Kimberling_, Jul 04 2012

%F Sum_{n>=2} (-1)^n/a(n) = Pi/16 + 3*log(2)/8. - _Amiram Eldar_, Dec 18 2021

%F E.g.f.: 6 + (4*x - 5)*exp(x) - exp(-x). - _David Lovler_, Jul 22 2022

%t {#,#+2}&/@(8*Range[0,30])//Flatten (* or *) LinearRecurrence[{1,1,-1},{0,2,8},60] (* _Harvey P. Dale_, Nov 30 2019 *)

%o (PARI) forstep(n=0,200,[2,6],print1(n", ")) \\ _Charles R Greathouse IV_, Oct 17 2011

%o (PARI) a(n) = 4*n - 5 - (-1)^n; \\ _David Lovler_, Jul 25 2022

%Y Union of A008590 and A017089.

%Y Cf. A030308, A042948.

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_

%E More terms from _Vincenzo Librandi_, Aug 06 2010