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 A301580 #13 May 26 2018 22:24:00 %S A301580 3,23,95,8063,122879,393215,2146959359,2305843007066210303, %T A301580 618970017336847128235868159,162258657859193720701440560726015, %U A301580 170141021201192402518323912137873817599 %N A301580 a(n) is the number of positive integers between successive Mersenne primes. %H A301580 Caldwell and Honaker, <a href="https://primes.utm.edu/curios/page.php?number_id=16918">61897...68159 (27-digits)</a>, Prime Curios! %F A301580 a(n) = A139231(n) - 1. - _Omar E. Pol_, Mar 23 2018 %e A301580 a(2) = 23 because there are 23 positive integers between successive Mersenne primes 7 and 31. %t A301580 -1 + Differences@ Array[2^MersennePrimeExponent[#] - 1 &, 12] (* _Michael De Vlieger_, Apr 21 2018 *) %Y A301580 Cf. A000668, A139231. %K A301580 nonn %O A301580 1,1 %A A301580 _G. L. Honaker, Jr._, Mar 23 2018