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 A232229 #18 Mar 11 2025 08:41:49
%S A232229 9,97,905,8913,88921,888929,8888937,88888945,888888953,8888888961,
%T A232229 88888888969,888888888977,8888888888985,88888888888993,
%U A232229 888888888889001,8888888888889009,88888888888889017,888888888888889025,8888888888888889033,88888888888888889041,888888888888888889049,8888888888888888889057
%N A232229 a(1)=9; thereafter a(n) = 8*10^(n-1) + 8 + a(n-1).
%C A232229 An infinite subsequence of A003052.
%H A232229 D. W. Bange, <a href="http://www.jstor.org/stable/2319017">Solution to Problem E 2408</a>, Amer. Math. Monthly, 81 (1974), 407.
%H A232229 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_9">On Some Marvellous Numbers of Kaprekar</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.
%H A232229 <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>
%H A232229 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (12,-21,10)
%F A232229 G.f.: x*(-9+11*x+70*x^2) / ( (10*x-1)*(x-1)^2 ). a(n) = (8*10^n-71)/9+8*n. - _R. J. Mathar_, Nov 24 2013
%p A232229 f:=proc(n) option remember; if n=1 then 9 else
%p A232229 8*10^(n-1)+8+f(n-1); fi; end;
%p A232229 [seq(f(n),n=1..40)];
%t A232229 RecurrenceTable[{a[1]==9,a[n]==8*10^(n-1)+8+a[n-1]},a,{n,30}] (* _Harvey P. Dale_, May 19 2018 *)
%Y A232229 Cf. A003052, A010061.
%K A232229 nonn,easy
%O A232229 1,1
%A A232229 _N. J. A. Sloane_, Nov 22 2013
%E A232229 Definition corrected by _Harvey P. Dale_, May 19 2018