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a(n) = Sum_{k=1..n} C(n-k, floor((n-k)/k)).
3

%I #8 May 28 2021 03:40:40

%S 0,1,2,3,5,7,13,19,34,61,108,174,384,641,1166,2337,4458,7828,16421,

%T 29346,57231,114126,215915,396491,839324,1549146,2983185,5978656,

%U 11628952,21812113,45099914,84842925,166417181,332267593,647614074,1234586894,2538571022

%N a(n) = Sum_{k=1..n} C(n-k, floor((n-k)/k)).

%F a(n) ~ 2^(n - 3/2) / sqrt(Pi*n). - _Vaclav Kotesovec_, May 28 2021

%p A273161:=n->add(binomial(n-i,floor((n-i)/i)), i=1..n): seq(A273161(n), n=0..50);

%t Table[Sum[Binomial[n - i, Floor[(n - i)/i]], {i, n}], {n, 0, 40}]

%Y Cf. A051054, A273160.

%K nonn,easy

%O 0,3

%A _Wesley Ivan Hurt_, May 16 2016