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A120134
a(n) = 4 + floor(Sum_{k=1..n-1} a(k) / 2).
13
4, 6, 9, 13, 20, 30, 45, 67, 101, 151, 227, 340, 510, 765, 1148, 1722, 2583, 3874, 5811, 8717, 13075, 19613, 29419, 44129, 66193, 99290, 148935, 223402, 335103, 502655, 753982, 1130973, 1696460, 2544690, 3817035, 5725552, 8588328, 12882492
OFFSET
1,1
LINKS
FORMULA
a(n) ~ c * (3/2)^n, where c = 3.9320886310283094862025842648411406926537121258867950257873967568454133192... - Vaclav Kotesovec, May 07 2023
MAPLE
a := proc(n) option remember; 4 + iquo(add(a(k), k = 1..n-1), 2) end:
seq(a(n), n = 1..37); # Peter Luschny, May 07 2023
MATHEMATICA
f[s_]:= Append[s, 4+Floor[Plus @@ s/2]]; Nest[f, {4}, 37] (* Robert G. Wilson v, Jun 10 2006 *)
PROG
(SageMath)
@CachedFunction
def A120134(n): return 4 + sum(A120134(k) for k in range(1, n))//2
print([A120134(n) for n in range(1, 41)]) # G. C. Greubel, May 07 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Graeme McRae, Jun 10 2006
EXTENSIONS
Name edited by Peter Luschny, May 07 2023
STATUS
approved