login
a(n) = 10 + floor(Sum_{j=1..n-1} a(j) / 2).
3

%I #15 May 14 2023 12:37:31

%S 10,15,22,33,50,75,112,168,252,378,567,851,1276,1914,2871,4307,6460,

%T 9690,14535,21803,32704,49056,73584,110376,165564,248346,372519,

%U 558779,838168,1257252,1885878,2828817,4243226,6364839,9547258,14320887

%N a(n) = 10 + floor(Sum_{j=1..n-1} a(j) / 2).

%H G. C. Greubel, <a href="/A120138/b120138.txt">Table of n, a(n) for n = 1..1000</a>

%t a[n_]:= a[n]= 10 +Quotient[Sum[a[k], {k,n-1}],2];

%t Table[a[n], {n,60}] (* _G. C. Greubel_, May 08 2023 *)

%o (SageMath)

%o @CachedFunction

%o def A120138(n): return 10 +sum(A120138(k) for k in range(1,n))//2

%o [A120138(n) for n in range(1,60)] # _G. C. Greubel_, May 08 2023

%Y Cf. A073941, A072493, A112088, A120134 - A120137, A120139 - A120209.

%K nonn

%O 1,1

%A _Graeme McRae_, Jun 10 2006