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 A100956 #5 Jul 19 2012 04:08:04
%S A100956 2,2,141,2,545,5,141,282,111,3,141,5,131,282,141,141,9,3,2,303,171,6,
%T A100956 222,323,2,393,797,606,191,404,414,363,797,171,474,737,25752,545,
%U A100956 20502,14241,848,12821,15951,474,575,12321,2,17771,8,666,14541,15651,171,191
%N A100956 Consider all (2n+1)-digit palindromic primes of the form 70...0M0...07 (so that M is a palindrome with <= 2n-1 digits); a(n) = smallest such M.
%H A100956 Vincenzo Librandi, <a href="/A100956/b100956.txt">Table of n, a(n) for n = 1..200</a>
%t A100956 f[n_] := Block[{k = 0, t = Flatten[ Join[{7}, Table[0, {n - 1}]]]}, While[s = Drop[t, Min[ -Floor[ Log[10, k]/2], 0]]; k != FromDigits[ Reverse[ IntegerDigits[k]]] || !PrimeQ[ FromDigits[ Join[s, IntegerDigits[k], Reverse[s]]]], k++ ]; k]; Table[ f[n], {n, 55}]
%Y A100956 Cf. A100026, A100955, A100957.
%K A100956 base,nonn
%O A100956 1,1
%A A100956 _Robert G. Wilson v_, Nov 23 2004