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 A098640 #15 Nov 22 2022 02:35:03
%S A098640 5,9,33,129,2049,8193,131073,524289,8388609,536870913,2147483649,
%T A098640 137438953473,2199023255553,8796093022209,140737488355329,
%U A098640 9007199254740993,576460752303423489,2305843009213693953
%N A098640 a(n) = 2^p + 1 where p is the n-th prime.
%H A098640 Vincenzo Librandi, <a href="/A098640/b098640.txt">Table of n, a(n) for n = 1..200</a>
%F A098640 Product_{n>=1} (1 - 1/a(n)) = A184084. - _Amiram Eldar_, Nov 22 2022
%e A098640 If p=2, 2^2+1 = 5.
%e A098640 If p=7, 2^7+1 = 129.
%t A098640 Table[2^Prime[n] + 1, {n, 18}] (* _Robert G. Wilson v_, Nov 01 2004 *)
%o A098640 (Magma) [2^p+1: p in PrimesUpTo(100)]; // _Vincenzo Librandi_, Apr 29 2014
%o A098640 (PARI) a(n) = 2^prime(n) + 1; \\ _Amiram Eldar_, Nov 22 2022
%Y A098640 Cf. A184084.
%K A098640 nonn,easy
%O A098640 1,1
%A A098640 _Parthasarathy Nambi_, Oct 27 2004
%E A098640 More terms from _Robert G. Wilson v_, Nov 01 2004