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A147788
a(n) = floor(2*(3/2)^n).
3
2, 3, 4, 6, 10, 15, 22, 34, 51, 76, 115, 172, 259, 389, 583, 875, 1313, 1970, 2955, 4433, 6650, 9975, 14963, 22445, 33668, 50502, 75753, 113630, 170445, 255668, 383502, 575253, 862879, 1294319, 1941479, 2912219, 4368328, 6552493, 9828739, 14743109
OFFSET
0,1
COMMENTS
Different from the sequence defined by the recursion a(1) = 3, a(n) = floor(a(n-1)*3/2) for n > 1, which gives a(2) = 4, a(3) = 6, a(4) = 9, a(5) = 13, ... (cf. A061418). - Klaus Brockhaus, Nov 16 2008
EXAMPLE
a(4) = floor(2*(3/2)^4) = floor(81/8) = floor(10+1/8) = 10. - Klaus Brockhaus, Nov 16 2008
MATHEMATICA
lst={}; s=2; Do[s=s*1.5; AppendTo[lst, Floor[s]], {n, 1, 5!}]; lst
Floor[2 (3/2)^Range[0, 40]] (* Harvey P. Dale, Aug 28 2019 *)
PROG
(Magma) [ Floor(2*(3/2)^n):n in [1..39] ]; // Klaus Brockhaus, Nov 16 2008
(Python)
def A147788(n): return 3**n>>n-1 if n else 2 # Chai Wah Wu, Sep 21 2022
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
EXTENSIONS
Definition clarified by R. J. Mathar, Nov 14 2008
Edited by N. J. A. Sloane, Nov 18 2008
STATUS
approved