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 A277801 #19 Dec 29 2016 03:15:42
%S A277801 -1,-1,-1,1,5,19,47,109,233,483,993,2011,4055,8149,16337,32715,65477,
%T A277801 131011,262077,524217,1048503,2097073,4194221,8388519,16777119,
%U A277801 33554331,67108761,134217621,268435347,536870799,1073741697,2147483517,4294967159,8589934453,17179869035
%N A277801 a(n) = 2^(n - 1) - prime(n).
%C A277801 Obviously all terms are odd. Only the first three terms are negative.
%C A277801 The law of small numbers says there are not enough small numbers for all the demands placed on them.
%C A277801 I think one of those demands is that there be a strong correlation between the powers of 2 and the prime numbers. The first four primes and the first four powers of 2 deliver. But then the powers of 2 rise, literally, exponentially, leaving the primes behind in the dust.
%F A277801 a(n) is approximately 2^(n - 1).
%t A277801 Table[2^(n - 1) - Prime[n], {n, 35}]
%Y A277801 Cf. A111209.
%K A277801 sign,easy
%O A277801 1,5
%A A277801 _Alonso del Arte_, Oct 31 2016