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 A100955 #5 Jul 18 2012 19:56:20
%S A100955 1,1,1,2,5,2,2,8,5,434,5,313,272,838,5,272,8,505,1,7,212,7,151,686,2,
%T A100955 242,656,656,323,929,121,242,262,12521,454,949,353,2,16361,707,10301,
%U A100955 515,29092,454,13331,686,848,20602,1,484,737,101,242,121,15551,656,232
%N A100955 Consider all (2n+1)-digit palindromic primes of the form 30...0M0...03 (so that M is a palindrome with <= 2n-1 digits); a(n) = smallest such M.
%H A100955 Vincenzo Librandi, <a href="/A100955/b100955.txt">Table of n, a(n) for n = 1..200</a>
%t A100955 f[n_] := Block[{k = 0, t = Flatten[ Join[{3}, 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, 57}]
%Y A100955 Cf. A100026, A100956, A100957.
%K A100955 base,nonn
%O A100955 1,4
%A A100955 _Robert G. Wilson v_, Nov 23 2004