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A113841 a(n) = a(n-1) + 2^A047240(n) for n>1, a(1)=1.

%I A113841 #20 Jul 31 2015 18:11:20
%S A113841 1,3,7,71,199,455,4551,12743,29127,291271,815559,1864135,18641351,
%T A113841 52195783,119304647,1193046471,3340530119,7635497415,76354974151,
%U A113841 213793927623,488671834567,4886718345671,13682811367879,31274997412295
%N A113841 a(n) = a(n-1) + 2^A047240(n) for n>1, a(1)=1.
%H A113841 Vincenzo Librandi, <a href="/A113841/b113841.txt">Table of n, a(n) for n = 1..300</a>
%H A113841 Vladimir Pletser, <a href="http://arxiv.org/abs/1409.7969">Congruence conditions on the number of terms in sums of consecutive squared integers equal to squared integers</a>, arXiv:1409.7969 [math.NT], 2014.
%H A113841 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 64, -64).
%F A113841 G.f.: x*(1+2*x+4*x^2)/((-1+x)*(-1+4*x)*(1+4*x+16*x^2)). - _Vaclav Kotesovec_, Nov 28 2012
%F A113841 a(1)=1, a(2)=3, a(3)=7, a(4)=71, a(n)=a(n-1)+64*a(n-3)-64*a(n-4). - _Harvey P. Dale_, Nov 18 2013
%t A113841 CoefficientList[Series[(1 + 2 x + 4 x^2) / ((-1 + x) (-1 + 4 x) (1 + 4 x + 16 x^2)), {x, 0, 30}], x] (* _Vincenzo Librandi_, May 19 2013 *)
%t A113841 LinearRecurrence[{1,0,64,-64},{1,3,7,71},30] (* _Harvey P. Dale_, Nov 18 2013 *)
%Y A113841 Cf. A099974, A112627, A080355, A080567, A099969, A099970, A099971.
%K A113841 nonn,easy
%O A113841 1,2
%A A113841 _Artur Jasinski_, Jan 27 2006
%E A113841 Edited with better definition and offset corrected by _Omar E. Pol_, Jan 08 2009