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