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 A139231 #17 Sep 27 2024 05:42:16
%S A139231 4,24,96,8064,122880,393216,2146959360,2305843007066210304,
%T A139231 618970017336847128235868160,162258657859193720701440560726016,
%U A139231 170141021201192402518323912137873817600
%N A139231 First differences of Mersenne primes A000668.
%H A139231 Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%F A139231 a(n) = A000668(n+1) - A000668(n).
%e A139231 a(1)=4 because A000668(1)=3 and A000668(2)=7 then 7-3 = 4.
%t A139231 A000668 := Select[2^Range[1000] - 1, PrimeQ]; Table[A000668[[n + 1]] - A000668[[n]], {n, 1, 10}] (* _G. C. Greubel_, Oct 03 2017 *)
%t A139231 Differences[2^MersennePrimeExponent[Range[20]]-1] (* _Harvey P. Dale_, Mar 31 2022 *)
%o A139231 (PARI) a=0; b=0; forprime(p=1, 1e2, if(ispseudoprime(2^p-1) && a==0, a=2^p-1); if(ispseudoprime(2^p-1) && a!=0, b=2^p-1; if(a!=b, print1(b-a, ", ")); a=b)) \\ _Felix Fröhlich_, Aug 12 2014
%Y A139231 Cf. A000668, A139228, A139229, A139230, A139232, A139233, A139234, A139235, A139236, A139237.
%K A139231 nonn
%O A139231 1,1
%A A139231 _Omar E. Pol_, Apr 18 2008
%E A139231 a(8)-a(11) from _Felix Fröhlich_, Aug 12 2014