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 A084831 #10 Dec 15 2017 17:36:23
%S A084831 1,2,3,4,5,6,7,43,81,86,162,201,205,211,221,241,251,271,281,325,333,
%T A084831 344,365,422,433,443,463,482,489,519,559,633,650,685,730,793,803,827,
%U A084831 857,866,877,886,887,1419,1505,1841,2021,2111,2221,2305,2441,2551,2561,2611
%N A084831 Numbers n such that sum of odd divisors and sum of even divisors are both palindromic.
%C A084831 Primes of form 2*10^n + R(n) (A056700) and 2/9*(-1+10^n)-1 (A084832) are members.
%H A084831 Harvey P. Dale, <a href="/A084831/b084831.txt">Table of n, a(n) for n = 1..1000</a>
%e A084831 a(11)=162 because sum of even divisors is 242 and sum of odd divisors is 121.
%t A084831 sodQ[n_]:=Module[{dn=Divisors[n],o,e},o=IntegerDigits[Total[Select[ dn,OddQ]]]; e=IntegerDigits[Total[Select[dn,EvenQ]]]; o== Reverse[o] && e==Reverse[e]]; Select[Range[3000],sodQ] (* _Harvey P. Dale_, Feb 27 2013 *)
%Y A084831 Cf. A000593, A056700, A084832.
%K A084831 base,nonn
%O A084831 1,2
%A A084831 _Jason Earls_, Jun 05 2003