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%I #7 Dec 26 2023 11:23:16
%S 4,5,6,7,9,10,12,15,18,21,26,31,37,44,53,64,77,92,110,132,159,191,229,
%T 275,330,396,475,570,684,821,985,1182,1418,1702,2042,2451,2941,3529,
%U 4235,5082
%N a(n) = 4 + floor((3 + Sum_{j=1..n-1} a(j))/5).
%H G. C. Greubel, <a href="/A120173/b120173.txt">Table of n, a(n) for n = 1..10000</a>
%t A120173[n_]:= A120173[n]= 4 +Floor[(3 +Sum[a[j], {j,n-1}])/5];
%t Table[A120173[n], {n, 60}] (* _G. C. Greubel_, Dec 26 2023 *)
%o (Magma)
%o function f(n, a, b)
%o t:=0;
%o for k in [1..n-1] do
%o t+:= a+Floor((b+t)/5);
%o end for;
%o return t;
%o end function;
%o g:= func< n, a, b | f(n+1, a, b)-f(n, a, b) >;
%o A120173:= func< n | g(n, 4, 3) >;
%o [A120173(n): n in [1..60]]; // _G. C. Greubel_, Dec 26 2023
%o (SageMath)
%o @CachedFunction
%o def f(n, p, q): return p + (q +sum(f(k, p, q) for k in range(1, n)))//5
%o def A120173(n): return f(n, 4, 3)
%o [A120173(n) for n in range(1, 61)] # _G. C. Greubel_, Dec 26 2023
%Y Cf. A073941, A072493, A112088.
%K nonn
%O 1,1
%A _Graeme McRae_, Jun 10 2006
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