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A120168
a(n) = 11 + floor(Sum_{j-1..n-1} a(j)/4).
3
11, 13, 17, 21, 26, 33, 41, 51, 64, 80, 100, 125, 156, 195, 244, 305, 381, 476, 595, 744, 930, 1163, 1453, 1817, 2271, 2839, 3548, 4435, 5544, 6930, 8663, 10828, 13535, 16919, 21149, 26436, 33045, 41306, 51633, 64541
OFFSET
1,1
LINKS
MATHEMATICA
f[n_, p_, q_]:= f[n, p, q]= p +Quotient[q +Sum[f[k, p, q], {k, n-1}], 4];
A120168[n_]:= f[n, 11, 0];
Table[A120168[n], {n, 60}] (* G. C. Greubel, Sep 09 2023 *)
PROG
(Magma)
function f(n, a, b)
t:=0;
for k in [1..n-1] do
t+:= a+Floor((b+t)/4);
end for;
return t;
end function;
g:= func< n, a, b | f(n+1, a, b)-f(n, a, b) >;
A120168:= func< n | g(n, 11, 0) >;
[A120168(n): n in [1..60]]; // G. C. Greubel, Sep 09 2023
(SageMath)
@CachedFunction
def f(n, p, q): return p + (q +sum(f(k, p, q) for k in range(1, n)))//4
def A120168(n): return f(n, 11, 0)
[A120168(n) for n in range(1, 61)] # G. C. Greubel, Sep 09 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Graeme McRae, Jun 10 2006
STATUS
approved