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a(n) = floor(n*2^n/(n + 1)).
2

%I #10 Dec 27 2021 23:46:52

%S 0,1,2,6,12,26,54,112,227,460,930,1877,3780,7606,15291,30720,61680,

%T 123790,248346,498073,998643,2001826,4011942,8039082,16106127,

%U 32263876,64623350,129424237,259179060,518975214,1039104990,2080374784,4164816771,8337289456,16689015778

%N a(n) = floor(n*2^n/(n + 1)).

%H Robert Israel, <a href="/A350294/b350294.txt">Table of n, a(n) for n = 0..3305</a>

%H Heiko Harborth and Hauke Nienborg, <a href="https://www.researchgate.net/publication/266861957_Saturated_vertex_Turan_numbers_for_cube_graphs">Saturated vertex TurĂ¡n numbers for cube graphs</a>, Congr. Num. 208 (2011), 183-188.

%H Mathonline, <a href="http://mathonline.wikidot.com/cube-graphs">Cube Graphs</a>

%F A350293(n) <= a(n) (see Lemma 1 in Harborth and Nienborg).

%F a(n) ~ 2^n.

%p f:= n -> floor(n*2^n/(n+1)):

%p map(f, [$0..40]); # _Robert Israel_, Dec 27 2021

%t Table[Floor[n 2^n/(n+1)],{n,0,34}]

%Y Cf. A000079, A350293.

%K nonn

%O 0,3

%A _Stefano Spezia_, Dec 23 2021