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 A073715 #16 Oct 30 2024 21:59:07
%S A073715 2,5,29,113,8179,131063,524269,2147483629,2305843009213693921,
%T A073715 618970019642690137449562091,162259276829213363391578010287957,
%U A073715 170141183460469231731687303715884105703
%N A073715 Prime preceding the n-th Mersenne prime.
%H A073715 Amiram Eldar, <a href="/A073715/b073715.txt">Table of n, a(n) for n = 1..18</a>
%F A073715 a(n) = prime(primepi(A000668(n))-1).
%F A073715 From _Amiram Eldar_, Aug 10 2024: (Start)
%F A073715 a(n) = A151799(A000668(n)).
%F A073715 a(n) = A000668(n) - A365161(n). (End)
%p A073715 a:= n-> prevprime(numtheory[mersenne]([n])):
%p A073715 seq(a(n), n=1..12); # _Alois P. Heinz_, Oct 30 2024
%t A073715 NextPrime[Select[2^Prime[Range[50]] - 1, PrimeQ], -1] (* _Jayanta Basu_, Jul 08 2013 *)
%t A073715 Table[NextPrime[2^MersennePrimeExponent[n] - 1, -1], {n, 1, 12}] (* _Amiram Eldar_, Aug 10 2024 *)
%Y A073715 Cf. A000668, A074626, A151799, A365161.
%K A073715 nonn,hard
%O A073715 1,1
%A A073715 _Labos Elemer_, Aug 05 2002