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 A109929 #14 Sep 25 2019 04:24:11
%S A109929 1,252,180081,855558,335323533,1072288822701,1338059508331,
%T A109929 770589909985077,97777777779,98888888889,1109887655445567889011,
%U A109929 739760991261414162199067937,33436553118011488411081135563433,4447899705293460330643925079987444,551190490170920715517029071094091155
%N A109929 Least palindromic multiple of concatenation n,n-1,n-2,...3,2,1.
%C A109929 a(12) > 10^25. - _Donovan Johnson_, Mar 28 2011
%t A109929 f[n_] := Block[{k = 1, p = FromDigits[ Flatten[ IntegerDigits /@ Range[n, 1, -1]]]}, While[k p != FromDigits[ Reverse[ IntegerDigits[k p]]], k++ ]; k p]; Table[ f[n], {n, 11}] (* _Robert G. Wilson v_ *)
%Y A109929 Cf. A109924.
%K A109929 base,nonn
%O A109929 1,2
%A A109929 _Amarnath Murthy_, Jul 18 2005
%E A109929 Edited, corrected and extended (a(3) - a(10)) by _Robert G. Wilson v_, Jul 21 2005
%E A109929 a(11) from _Donovan Johnson_, Mar 28 2011
%E A109929 a(12)-a(15) from _Giovanni Resta_, Sep 23 2019