This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A147595 #24 Oct 26 2022 03:05:13
%S A147595 1,3,7,15,27,51,99,195,387,771,1539,3075,6147,12291,24579,49155,98307,
%T A147595 196611,393219,786435,1572867,3145731,6291459,12582915,25165827,
%U A147595 50331651,100663299,201326595,402653187,805306371,1610612739,3221225475
%N A147595 a(n) is the number whose binary representation is A138144(n).
%H A147595 Harvey P. Dale, <a href="/A147595/b147595.txt">Table of n, a(n) for n = 1..1000</a>
%H A147595 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2).
%F A147595 a(n) = A060013(n+2), n > 3. - _R. J. Mathar_, Feb 05 2010
%F A147595 a(n+4) = 3*(2^(n+2) + 1), n >= 0. - _Brad Clardy_, Apr 03 2013
%F A147595 From _Colin Barker_, Sep 15 2013: (Start)
%F A147595 a(n) = 3*(4 + 2^n)/4 for n>3.
%F A147595 a(n) = 3*a(n-1) - 2*a(n-2).
%F A147595 G.f.: x*(1-2*x^2)*(1+2*x^2) / ((1-x)*(1-2*x)). (End)
%F A147595 E.g.f.: (3/4)*(4*exp(x) + exp(2*x)) - (15/4) - 7*x/2 - 3*x^2/2 - x^3/3. - _G. C. Greubel_, Oct 25 2022
%t A147595 LinearRecurrence[{3,-2},{1,3,7,15,27},40] (* _Harvey P. Dale_, Nov 30 2020 *)
%o A147595 (PARI) Vec(-x*(2*x^2-1)*(2*x^2+1)/((x-1)*(2*x-1)) + O(x^100)) \\ _Colin Barker_, Sep 15 2013
%o A147595 (Magma) [1,3,7] cat [3*(1+2^(n-2)): n in [4..40]]; // _G. C. Greubel_, Oct 25 2022
%o A147595 (SageMath) [1,3,7]+[3*(1+2^(n-2)) for n in range(4,40)] # _G. C. Greubel_, Oct 25 2022
%Y A147595 Cf. A138144, A145641, A147537, A147538, A147539, A147540, A147590, A147596, A147597.
%K A147595 base,easy,nonn
%O A147595 1,2
%A A147595 _Omar E. Pol_, Nov 08 2008
%E A147595 Extended by _R. J. Mathar_, Feb 05 2010