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 A090064 #9 Nov 30 2013 11:47:52 %S A090064 18,27,36,45,54,63,69,72,78,81,87,90,96,99,113,125,126,128,137,146, %T A090064 149,156,157,162,163,165,168,169,172,175,180,183,188,189,193,194,195, %U A090064 197,220,224,225,227,232,236,242,245,248,252,255,256,259,261,264,267,268 %N A090064 Numbers n such that there are (presumably) three palindromes in the Reverse and Add! trajectory of n. %C A090064 For terms < 2000 each palindrome is reached from the preceding one or from the start in at most 24 steps; after the presumably last one no further palindrome is reached in 2000 steps. %H A090064 <a href="/index/Res#RAA">Index entries for sequences related to Reverse and Add!</a> %e A090064 The trajectory of 113 begins 113, 424, 848, 1696, 8657, 16225, 68486, 136972, 416603, ...; at 416603 it joins the (presumably) palindrome-free trajectory of A063048(16) = 10735, hence 424, 848 and 68486 are the three palindromes in the trajectory of 113 and 113 is a term. %Y A090064 Cf. A023108, A023109, A065001, A070742, A077594. %K A090064 nonn,base %O A090064 1,1 %A A090064 _Klaus Brockhaus_, Nov 20 2003