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a(n) = 7*n + 6.
15

%I #37 Dec 28 2023 22:06:27

%S 6,13,20,27,34,41,48,55,62,69,76,83,90,97,104,111,118,125,132,139,146,

%T 153,160,167,174,181,188,195,202,209,216,223,230,237,244,251,258,265,

%U 272,279,286,293,300,307,314,321,328,335,342,349,356,363,370,377,384

%N a(n) = 7*n + 6.

%H Vincenzo Librandi, <a href="/A017053/b017053.txt">Table of n, a(n) for n = 0..5000</a>

%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>

%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=955">Encyclopedia of Combinatorial Structures 955</a>

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).

%F a(n) = 2*a(n-1) - a(n-2). - _Wesley Ivan Hurt_, Mar 17 2023

%F G.f.: (6+x)/(1-x)^2. - _Wesley Ivan Hurt_, Dec 28 2023

%t Array[7*#+6&,100,0] (* _Vladimir Joseph Stephan Orlovsky_, Dec 14 2009 *)

%t LinearRecurrence[{2,-1},{6,13},60] (* _Harvey P. Dale_, Apr 13 2022 *)

%o (Magma) [7*n + 6: n in [0..60]]; // _Vincenzo Librandi_, Jun 18 2011

%o (PARI) a(n)=7*n+6 \\ _Charles R Greathouse IV_, Jul 10 2016

%Y Cf. A008589, A016993, A017005, A017017.

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_