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 A106388 Numbers k such that 11k = 6j^2 + 6j + 1. 4

%I

%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

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Last modified October 14 14:45 EDT 2019. Contains 328019 sequences. (Running on oeis4.)