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 A218729 #20 Aug 29 2024 17:44:34
%S A218729 0,1,27,703,18279,475255,12356631,321272407,8353082583,217180147159,
%T A218729 5646683826135,146813779479511,3817158266467287,99246114928149463,
%U A218729 2580398988131886039,67090373691429037015,1744349715977154962391,45353092615406029022167,1179180408000556754576343
%N A218729 a(n) = (26^n - 1)/25.
%C A218729 Partial sums of powers of 26 (A009970); q-integers for q=26.
%H A218729 Vincenzo Librandi, <a href="/A218729/b218729.txt">Table of n, a(n) for n = 0..700</a>
%H A218729 <a href="/index/Par#partial">Index entries related to partial sums</a>.
%H A218729 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (27,-26).
%F A218729 From _Vincenzo Librandi_, Nov 07 2012: (Start)
%F A218729 G.f.: x/((1-x)*(1-26*x)).
%F A218729 a(n) = floor(26^n/25).
%F A218729 a(n) = 27*a(n-1) - 26*a(n-2). (End)
%F A218729 E.g.f.: exp(x)*(exp(25*x) - 1)/25. - _Elmo R. Oliveira_, Aug 29 2024
%t A218729 LinearRecurrence[{27, -26}, {0, 1}, 30] (* _Vincenzo Librandi_, Nov 07 2012 *)
%o A218729 (PARI) A218729(n)=26^n\25
%o A218729 (Magma) [n le 2 select n-1 else 27*Self(n-1)-26*Self(n-2): n in [1..20]]; // _Vincenzo Librandi_, Nov 07 2012
%o A218729 (Maxima) A218729(n):=(26^n-1)/25$
%o A218729 makelist(A218729(n),n,0,30); /* _Martin Ettl_, Nov 07 2012 */
%Y A218729 Cf. similar sequences of the form (k^n-1)/(k-1): A000225, A003462, A002450, A003463, A003464, A023000, A023001, A002452, A002275, A016123, A016125, A091030, A135519, A135518, A131865, A091045, A218721, A218722, A064108, A218724-A218734, A132469, A218736-A218753, A133853, A094028, A218723.
%Y A218729 Cf. A009970.
%K A218729 nonn,easy
%O A218729 0,3
%A A218729 _M. F. Hasler_, Nov 04 2012