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A026806 a(n) = number of numbers k such that only one partition of n has least part k.

%I A026806 #16 Mar 06 2023 02:59:05
%S A026806 1,2,1,2,2,2,2,3,2,3,3,3,3,4,3,4,4,4,4,5,4,5,5,5,5,6,5,6,6,6,6,7,6,7,
%T A026806 7,7,7,8,7,8,8,8,8,9,8,9,9,9,9,10,9,10,10,10,10,11,10,11,11,11,11,12,
%U A026806 11,12,12,12,12,13,12,13,13,13,13,14,13,14,14,14,14,15,14,15,15,15,15
%N A026806 a(n) = number of numbers k such that only one partition of n has least part k.
%H A026806 G. C. Greubel, <a href="/A026806/b026806.txt">Table of n, a(n) for n = 1..1000</a>
%H A026806 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (0,1,1,0,-1).
%F A026806 G.f.: x*(1+2*x-x^3-x^4)/((1-x^2)*(1-x^3)).
%F A026806 a(n) = A008615(n+6) = 1 + A008615(n), n>0.
%p A026806 seq(1+floor(n/2)-floor(n/3), n = 0..90); # _G. C. Greubel_, Nov 09 2019
%t A026806 Rest[CoefficientList[Series[x(1+2x-x^3-x^4)/((1-x^2)(1-x^3)), {x,0,90}], x]]  (* _Harvey P. Dale_, Apr 22 2011 *)
%t A026806 Table[1 + Floor[n/2] - Floor[n/3], {n, 90}] (* _G. C. Greubel_, Nov 09 2019 *)
%o A026806 (PARI) a(n)=if(n<1,0,1+(n\2)-(n\3))
%o A026806 (Magma) [1+Floor(n/2)-Floor(n/3): n in [1..90]]; // _G. C. Greubel_, Nov 09 2019
%o A026806 (Sage) [1+floor(n/2)-floor(n/3) for n in (1..40)] # _G. C. Greubel_, Nov 09 2019
%o A026806 (GAP) List([1..90], n-> 1+Int(n/2)-Int(n/3) ); # _G. C. Greubel_, Nov 09 2019
%Y A026806 Cf. A008615.
%K A026806 nonn,easy
%O A026806 1,2
%A A026806 _Clark Kimberling_