%I #23 Jul 26 2018 15:14:44
%S 11,23,131,167,383,443,767,851,1283,1391,1931,2063,2711,2867,3623,
%T 3803,4667,4871,5843,6071,7151,7403,8591,8867,10163,10463,11867,12191,
%U 13703,14051,15671,16043,17771,18167,20003,20423,22367,22811,24863,25331,27491,27983
%N Numbers k such that 11k = 6j^2 + 6j + 1.
%C j sequence = A106387
%H Harvey P. Dale, <a href="/A106388/b106388.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1).
%F a(1)=11, a(2)=23; if n odd a(n)=a(n-1)+54*(n-1), if n even a(n)=a(n-1)+12*(n-1).
%F a(n) = (66*n*(n-1)-21*(2*n-1)*(-1)^n+23)/4.
%F G.f.: x*(11+12*x+86*x^2+12*x^3+11*x^4)/((1+x)^2*(1-x)^3).
%F a(n)-a(n-1)-2*a(n-2)+2*a(n-3)+a(n-4)-a(n-5) = 0 for n>5.
%t LinearRecurrence[{1,2,-2,-1,1},{11,23,131,167,383},50] (* _Harvey P. Dale_, Jul 26 2018 *)
%o (PARI) Vec((11+12*x+86*x^2+12*x^3+11*x^4)/(1+x)^2/(1-x)^3+O(x^99)) \\ _Charles R Greathouse IV_, Dec 28 2011
%Y Cf. A106387, A106389, A106390.
%K nonn,easy
%O 1,1
%A _Pierre CAMI_, May 01 2005
%E Formulae corrected and added by _Bruno Berselli_, Nov 16 2010
%E More terms from _Colin Barker_, Apr 16 2014