%I #8 Nov 27 2019 01:13:58
%S 4,22,121,202,1111,2002,10201,11011,20002,101101,110011,200002,
%T 1002001,1010101,1100011,2000002,10011001,10100101,11000011,20000002,
%U 100020001,100101001,101000101,110000011,200000002,1000110001,1001001001
%N Palindromes whose digit sum is 4.
%C There are ceiling(k/2) terms with k digits and so floor(n^2/4) terms with fewer than k digits. Writing the terms as a vertical column and then blanking zeros produces a narrow triangle with upward chevrons.
%Y Cf. A062397 and A066138 for digit sums of 2 and 3.
%K base,nonn
%O 1,1
%A _Henry Bottomley_, Dec 10 2001