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 A014931 #21 May 22 2025 01:02:50
%S A014931 1,33,801,17185,344865,6636321,124076833,2271560481,40926266145,
%T A014931 728121033505,12822748939041,223928981472033,3883103678710561,
%U A014931 66933498461897505,1147797409030816545,19594541482740368161,333189190735802745633,5645851483964153611041,95370814658487412671265
%N A014931 a(1)=1, a(n) = n*16^(n-1) + a(n-1).
%H A014931 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (33,-288,256).
%F A014931 G.f.: x/((1 - x)*(1 - 16*x)^2). - _Stefano Spezia_, Mar 11 2020
%F A014931 From _Elmo R. Oliveira_, May 21 2025: (Start)
%F A014931 E.g.f.: exp(x)*(1 + exp(15*x)*(240*x - 1))/225.
%F A014931 a(n) = (16^n*(15*n - 1) + 1)/225.
%F A014931 a(n) = 32*a(n-1) - 256*a(n-2) + 1 for n > 2.
%F A014931 a(n) = 33*a(n-1) - 288*a(n-2) + 256*a(n-3) for n > 3. (End)
%t A014931 RecurrenceTable[{a[1]==1,a[n]==n*16^(n-1)+a[n-1]},a,{n,20}] (* _Harvey P. Dale_, Sep 17 2019 *)
%o A014931 (PARI) a(n) = (1+16^n*(15*n-1))/225; \\ _Jinyuan Wang_, Mar 11 2020
%o A014931 (PARI) Vec(-x/((x-1)*(16*x-1)^2) + O(x^20)) \\ _Elmo R. Oliveira_, May 21 2025
%K A014931 nonn,easy
%O A014931 1,2
%A A014931 _Olivier Gérard_
%E A014931 More terms from _Elmo R. Oliveira_, May 21 2025