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 A152099 #19 Jun 26 2023 19:01:35
%S A152099 15,63,1023,16383,4194303,67108863,17179869183,274877906943,
%T A152099 70368744177663,288230376151711743,4611686018427387903,
%U A152099 18889465931478580854783,4835703278458516698824703,77371252455336267181195263,19807040628566084398385987583
%N A152099 a(n) = (2^prime(n) - 1)*(2^prime(n) + 1) = 2^(2*prime(n)) - 1.
%C A152099 Idea resulted from seqfan posts by _Artur Jasinski_.
%F A152099 a(n) = A001348(n) * A098640(n).
%F A152099 a(n) = A034785(n)^2 - 1.
%F A152099 a(n) = A000302(A000040(n)) - 1.
%t A152099 Table[(2^Prime[n] - 1)*(2^Prime[n] + 1), {n, 1, 20}]
%o A152099 (Python)
%o A152099 from sympy import prime
%o A152099 def A152099(n): return (1<<(prime(n)<<1))-1 # _Chai Wah Wu_, Jun 26 2023
%Y A152099 Cf. A000040, A000302, A001348, A034785, A098640.
%K A152099 nonn
%O A152099 1,1
%A A152099 _Roger L. Bagula_, Nov 24 2008