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2n + 6.
2

%I #19 Apr 24 2017 18:02:16

%S 6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,

%T 52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,90,92,94,96,

%U 98,100,102,104,106,108,110,112,114,116,118,120,122,124,126,128,130,132,134,136,138

%N 2n + 6.

%C Pisot sequence T(6,8).

%C Trivial case of a Pisot sequence satisfying a simple linear recurrence. Here, since round((2n+2)^2/(2n)^2) = 2n + round((n+1)/n^2) = 2n for n>2, a(n) is even and a(n) = a(n-1) + 2. - _Ralf Stephan_, Sep 03 2013

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

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

%F a(n) = 2a(n-1) - a(n-2).

%t 2*Range[0,70]+6 (* or *) Range[6,138,2] (* _Harvey P. Dale_, Apr 24 2017 *)

%Y Subsequence of A005843. See A008776 for definitions of Pisot sequences.

%K nonn,easy

%O 0,1

%A _David W. Wilson_

%E Better name from _Ralf Stephan_, Sep 03 2013