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 A155803 #35 Jul 25 2024 03:44:45
%S A155803 0,0,0,1,2,4,9,18,36,73,146,292,585,1170,2340,4681,9362,18724,37449,
%T A155803 74898,149796,299593,599186,1198372,2396745,4793490,9586980,19173961,
%U A155803 38347922,76695844,153391689,306783378,613566756,1227133513,2454267026,4908534052
%N A155803 A023001 interleaved with 2*A023001 and 4*A023001.
%C A155803 A033138 with three zeros prepended. - _Joerg Arndt_, Mar 10 2015
%H A155803 Vincenzo Librandi, <a href="/A155803/b155803.txt">Table of n, a(n) for n = 0..1000</a>
%H A155803 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,1,-2).
%F A155803 a(3n) = A023001(n). a(3n+1) = 2*A023001(n) = A125835(n). a(3n+2) = 4*A023001(n).
%F A155803 a(n) = a(n-3)+2^(n-3) = a(n-3)+A000079(n-3). Here, a(.) can also be one of its higher order differences.
%F A155803 a(n) = 2*a(n-1)+a(n-3)-2*a(n-4). G.f.: x^3/((x-1)*(2*x-1)*(1+x+x^2)). [_R. J. Mathar_, Jul 23 2009]
%F A155803 a(n) = floor(2^n/7). [_Mircea Merca_, Dec 22 2010]
%p A155803 A023001 := proc(n) (8^n-1)/7; end: A155803 := proc(n) RETURN( A023001(n),2*A023001(n),4*A023001(n)) ; end: L := [seq(A155803(n),n=0..30)] ; # _R. J. Mathar_, Jul 23 2009
%p A155803 seq(floor(2^n/7),n=0..30) # _Mircea Merca_, Dec 22 2010
%t A155803 CoefficientList[Series[x^3/(1-2 x-x^3+2 x^4), {x,0,50}],x] (* _Harvey P. Dale_, Mar 13 2011 *)
%o A155803 (Magma) [Floor(2^n/7): n in [0..40]]; // _Vincenzo Librandi_, Sep 17 2011
%K A155803 nonn,easy
%O A155803 0,5
%A A155803 _Paul Curtz_, Jan 27 2009
%E A155803 Edited and extended by _R. J. Mathar_, Jul 23 2009