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 A111209 #19 Sep 08 2022 08:45:20
%S A111209 0,1,3,9,21,51,111,237,489,995,2017,4059,8151,16341,32721,65483,
%T A111209 131013,262083,524221,1048505,2097079,4194225,8388525,16777127,
%U A111209 33554335,67108763,134217625,268435349,536870803,1073741711,2147483521,4294967165,8589934455,17179869045
%N A111209 Difference between the powers of two and the primes.
%C A111209 2*a(n) < a(n+1) because 2*prime(n) > prime(n+1) (see A062234). We have a(n) - a(1) < a(n+1) - a(n) so this is a B_2 sequence. - _Thomas Ordowski_, Sep 23 2014
%F A111209 a(n) = 2^n - prime(n).
%F A111209 a(n) = A000079(n) - A000040(n). - _Wesley Ivan Hurt_, Sep 23 2014
%p A111209 A111209:=n->2^n-ithprime(n): seq(A111209(n), n=1..30); # _Wesley Ivan Hurt_, Sep 23 2014
%t A111209 Table[2^n - Prime[n], {n, 25}]
%o A111209 (PARI) vector(50, n, 2^n - prime(n)) \\ _Michel Marcus_, Sep 23 2014
%o A111209 (Magma) [2^n-NthPrime(n) : n in [1..30]]; // _Wesley Ivan Hurt_, Sep 23 2014
%Y A111209 Cf. A000040, A000079.
%K A111209 nonn,easy
%O A111209 1,3
%A A111209 _Roger L. Bagula_, Oct 25 2005
%E A111209 More terms from _Michel Marcus_, Sep 23 2014