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 A098815 #13 Feb 16 2025 08:32:54
%S A098815 -3,1,25,121,2041,8185,131065,524281,8388601,536870905,2147483641,
%T A098815 137438953465,2199023255545,8796093022201,140737488355321,
%U A098815 9007199254740985,576460752303423481,2305843009213693945,147573952589676412921,2361183241434822606841
%N A098815 2^p - 7 where p is prime.
%H A098815 Vincenzo Librandi, <a href="/A098815/b098815.txt">Table of n, a(n) for n = 1..200</a>
%H A098815 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RamanujansSquareEquation.html">Ramanujan's Square Equation</a>
%e A098815 If p = 3, then 2^3 - 7 = 1.
%e A098815 If p = 5, then 2^5 - 7 = 25.
%t A098815 Table[2^Prime[n] - 7, {n, 20}]
%o A098815 (Magma) [2^p-7: p in PrimesUpTo(100)]; // _Vincenzo Librandi_, Apr 29 2014
%K A098815 sign
%O A098815 1,1
%A A098815 _Parthasarathy Nambi_, Oct 07 2004
%E A098815 More terms from _Ray Chandler_, Nov 14 2004