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 A246808 #17 Sep 26 2014 17:29:53
%S A246808 2112,4803443084,6992662996,180461164081,214591195412,409473374904,
%T A246808 563715517365,4163019339103614,1050417996997140501
%N A246808 Palindromic terms of the sequence A245317.
%C A246808 For each n, A100414(n).reversal(A100414(n)) is in the sequence, where dot denotes concatenation. What is the first term of the sequence which is not of the above form?
%C A246808 a(9) <= 253385633342243336583352 and a(10) <= 661494322636636223494166.
%C A246808 a(9) = A245317(997140501) = 1050417996997140501 is the smallest term of the sequence which is not of the form A100414(n).reversal(A100414(n)). 253385633342243336583352 and 661494322636636223494166 are two consecutive terms of the sequence. - _Farideh Firoozbakht_, Sep 23 2014
%F A246808 For n<9, a(n) = A100414(n).reversal(A100414(n)).
%t A246808 h[n_]:=If[!PrimeQ[n],FromDigits[Flatten[{IntegerDigits[n],IntegerDigits[n-PrimePi[n]-1]}]]];Do[a=h[n];If[!PrimeQ[n]&&FromDigits[Reverse[IntegerDigits[a]]]==a,Print[a]],{n,100000000}]
%Y A246808 Cf. A002808, A004086, A100414, A245317.
%K A246808 nonn,base,more
%O A246808 1,1
%A A246808 _Jahangeer Kholdi_, Sep 17 2014
%E A246808 a(9) from _Farideh Firoozbakht_, Sep 23 2014