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 A135625 #9 Sep 18 2015 04:13:51
%S A135625 9,49,403,91567,15710338,22299240301,410215255975,
%T A135625 16028490260973271564,3675428737957071376458418697257441432,
%U A135625 68870283995769119153444423083582483731047501259451576,117132053040627211700855551462169332419627937481594387132326105147,123777964225587033644972609912682600644825032245501533642224841942296666013617
%N A135625 Product of n-th Mersenne prime and n-th Mersenne prime written backwards.
%H A135625 Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%F A135625 a(n) = A000668(n)*A135623(n).
%e A135625 a(3) = 403 because the 3rd Mersenne prime is 31 and 31*13 = 403.
%p A135625 read transforms : A000043 := proc(n) op(n,[2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, 9689, 9941, 11213, 19937]) ; end: A000668 := proc(n) 2^A000043(n)-1 ; end: A135623 := proc(n) digrev(A000668(n)) ; end: A135625 := proc(n) A000668(n)*A135623(n) ; end: for n from 1 to 13 do printf("%d, ",A135625 (n) ) ; od: # _R. J. Mathar_, Feb 28 2008
%t A135625 # FromDigits[Reverse[IntegerDigits[#]]]&/@Select[2^Prime[Range[100]]-1, PrimeQ] (* _Harvey P. Dale_, Mar 26 2012 *)
%Y A135625 Cf. A000668, A133019, A135623.
%K A135625 base,nonn
%O A135625 1,1
%A A135625 _Omar E. Pol_, Feb 20 2008
%E A135625 More terms from _R. J. Mathar_, Feb 28 2008