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 A298972 #8 Feb 02 2018 09:01:57
%S A298972 0,0,1,0,2,0,1,0,3,0,1,2,2,0,1,0,4,0,1,0,0,0,4,0,0,0,0,0,0,0,0,0,0,5,
%T A298972 0,0,0,0,0,0,0,0,0,0,8,0,0,0,0,0,0,0,0,0,0,6,0,0,0,0,0,0,0,0,0,0,11,0,
%U A298972 0,0,0,0,0,0,0,0,0,11,0,0,0,0,0,0,0,0
%N A298972 Number of positive integers k < n such that n occurs in the Reverse-and-Add trajectory of k.
%C A298972 Number of integers k < n such that n occurs in row k of A243238.
%C A298972 For n > 0, a(n) = 0 iff n is a term of A067031.
%C A298972 For n > 0, a(n) > 0 iff n is a term of A067030.
%H A298972 <a href="/index/Res#RAA">Index entries for sequences related to Reverse and Add!</a>
%e A298972 For n = 22: There exist 4 positive integers k < 22 such that 22 occurs in the Reverse-and-Add trajectory of k, namely 5, 10, 11 and 20, so a(22) = 4.
%t A298972 Block[{nn = 85, s}, s = Array[Union@ NestWhileList[# + IntegerReverse@ # &, #, # < nn &, 1, nn] &, nn]; Array[Count[Take[s, # - 1], #, 2] &, nn + 1, 0]] (* _Michael De Vlieger_, Feb 01 2018 *)
%o A298972 (PARI) a(n) = my(i=0); for(k=1, n-1, my(x=k); while(x < n, x=x+eval(concat(Vecrev(Str(x))))); if(x==n, i++)); i
%Y A298972 Cf. A056964, A067030, A067031, A243238.
%K A298972 nonn,base
%O A298972 0,5
%A A298972 _Felix Fröhlich_, Jan 30 2018