This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A047617 #41 Mar 30 2024 11:38:55
%S A047617 2,5,10,13,18,21,26,29,34,37,42,45,50,53,58,61,66,69,74,77,82,85,90,
%T A047617 93,98,101,106,109,114,117,122,125,130,133,138,141,146,149,154,157,
%U A047617 162,165,170,173,178,181,186,189,194,197,202,205,210,213,218,221,226,229,234
%N A047617 Numbers that are congruent to {2, 5} mod 8.
%C A047617 Numbers whose binary reflected Gray code (A014550) ends with 11. - _Amiram Eldar_, May 17 2021
%H A047617 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F A047617 a(n) = 8*n - a(n-1) - 9 (with a(1)=2). - _Vincenzo Librandi_, Aug 06 2010
%F A047617 a(n) = 4*n - (5 + (-1)^n)/2. - _Arkadiusz Wesolowski_, Sep 18 2012
%F A047617 G.f.: (2+3*x+3*x^2)/((-1+x)^2*(1+x)). - _Harvey P. Dale_, Feb 23 2016
%F A047617 a(1)=2, a(2)=5, a(3)=10, a(n) = a(n-1) + a(n-2) - a(n-3). - _Harvey P. Dale_, Feb 23 2016
%F A047617 From _Franck Maminirina Ramaharo_, Jul 22 2018: (Start)
%F A047617 a(n) = A047470(n) + 2.
%F A047617 E.g.f.: (6 - exp(-x) + (8*x - 5)*exp(x))/2. (End)
%F A047617 Sum_{n>=1} (-1)^(n+1)/a(n) = sqrt(2)*Pi/16 - log(2)/8 + sqrt(2)*log(sqrt(2)+1)/8. - _Amiram Eldar_, Dec 11 2021
%t A047617 Select[Range[300],MemberQ[{2,5},Mod[#,8]]&] (* or *) LinearRecurrence[ {1,1,-1},{2,5,10},80] (* _Harvey P. Dale_, Feb 23 2016 *)
%o A047617 (Maxima) makelist(4*n -(5 + (-1)^n)/2, n, 1, 100); /* _Franck Maminirina Ramaharo_, Jul 22 2018 */
%o A047617 (Python)
%o A047617 def A047617(n): return (n-1<<2)+1+(n&1) # _Chai Wah Wu_, Mar 30 2024
%Y A047617 Cf. A014550, A047398, A047452, A047461, A047470, A047524, A047535, A047615.
%K A047617 nonn,easy
%O A047617 1,1
%A A047617 _N. J. A. Sloane_
%E A047617 More terms from _Vincenzo Librandi_, Aug 06 2010