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A213255 2^(n-1) - floor((2^(n-1) - 1)/(n-1)).

%I A213255 #19 Sep 08 2024 19:26:05
%S A213255 1,3,6,13,26,54,110,225,456,922,1862,3755,7562,15214,30584,61441,
%T A213255 123362,247581,496694,996148,1997288,4003654,8023886,16078166,
%U A213255 32212255,64527754,129246702,258848476,518358122,1037950430,2078209982,4160749569,8329633544
%N A213255 2^(n-1) - floor((2^(n-1) - 1)/(n-1)).
%C A213255 Lower bounds of the decycling numbers of n-cubes for n >= 9.
%H A213255 Arkadiusz Wesolowski, <a href="/A213255/b213255.txt">Table of n, a(n) for n = 2..800</a>
%H A213255 Sheng Bau, <a href="http://arxiv.org/abs/math/0703544">The Decycling Number of Graphs</a>
%F A213255 a(n) = 2^(n-1) - floor((2^(n-1) - 1)/(n-1)).
%F A213255 a(n) = ceiling(2^(n-1) - (2^(n-1) - 1)/(n-1)).
%e A213255 a(8) = 110 because 2^7 - (2^7 - 1)/7 = 109.8571428571....
%t A213255 Table[Ceiling[2^(n - 1) - (2^(n - 1) - 1)/(n - 1)], {n, 2, 34}]
%o A213255 (Magma) [Ceiling(2^(n-1)-(2^(n-1)-1)/(n-1)) : n in [2..34]];
%o A213255 (PARI) for(n=2, 34, print1(ceil(2^(n-1)-(2^(n-1)-1)/(n-1)), ", "))
%Y A213255 Cf. A005009.
%K A213255 easy,nonn
%O A213255 2,2
%A A213255 _Arkadiusz Wesolowski_, Jun 07 2012