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 A081203 #20 Sep 08 2022 08:45:09 %S A081203 0,1,18,244,2952,33616,368928,3951424,41611392,432891136,4463129088, %T A081203 45705032704,465640261632,4725122093056,47800976744448, %U A081203 482407813955584,4859262511644672,48874100093157376,490992800745259008 %N A081203 9th binomial transform of (0,1,0,1,0,1,.....), A000035. %C A081203 Binomial transform of A081202. %C A081203 From _Wolfdieter Lang_, Jul 17 2017: (Start) %C A081203 For a combinatorial interpretation of a(n) with special 10-letter words of length n see the comment in A081200 on the 7-letter analog. %C A081203 The binomial transform of {a(n)}_{n >= 0} is {0, A016190}, the 11-letter analog. %C A081203 (End) %H A081203 Vincenzo Librandi, <a href="/A081203/b081203.txt">Table of n, a(n) for n = 0..200</a> %H A081203 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (18,-80). %F A081203 a(n) = 18*a(n-1)-80*a(n-2), a(0)=0, a(1)=1. %F A081203 G.f.: x/((1-8*x)*(1-10*x)). %F A081203 a(n) = 10^n/2 - 8^n/2. %t A081203 CoefficientList[Series[x / ((1 - 8 x) (1 - 10 x)), {x, 0, 20}], x] (* _Vincenzo Librandi_, Aug 07 2013 *) %t A081203 LinearRecurrence[{18,-80},{0,1},20] (* _Harvey P. Dale_, Aug 05 2018 *) %o A081203 (Magma) [10^n/2 - 8^n/2: n in [0..25]]; // _Vincenzo Librandi_, Aug 07 2013 %Y A081203 Apart from the first term, identical to A016186. %Y A081203 Cf. A000035, A016190, A081202, A081200, A081201, A081202. %K A081203 easy,nonn %O A081203 0,3 %A A081203 _Paul Barry_, Mar 11 2003