A120157 - OEIS

A120157

a(n) = 13 + floor(Sum_{j=1..n-1} a(j)/3).

13, 17, 23, 30, 40, 54, 72, 96, 128, 170, 227, 303, 404, 538, 718, 957, 1276, 1701, 2268, 3024, 4032, 5376, 7168, 9558, 12744, 16992, 22656, 30208, 40277, 53703, 71604, 95472, 127296, 169728, 226304, 301738, 402318, 536424, 715232, 953642

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

MATHEMATICA

Module[{lst={13}}, Do[AppendTo[lst, 13+Floor[Total[lst]/3]], {40}]; lst] (* Harvey P. Dale, May 22 2012 *)

PROG

(Magma)

function f(n, a, b)

t:=0;

for k in [1..n-1] do

t+:= a+Floor((b+t)/3);

end for;

return t;

end function;

g:= func< n, a, b | f(n+1, a, b)-f(n, a, b) >;

A120157:= func< n | g(n, 13, 0) >;

[A120157(n): n in [1..60]]; // G. C. Greubel, Aug 31 2023

(SageMath)

@CachedFunction

def A120157(n): return 13 +(sum(A120157(k) for k in range(1, n)))//3

[A120157(n) for n in range(1, 61)] # G. C. Greubel, Aug 31 2023

CROSSREFS

Cf. A072493, A073941, A112088.

Sequence in context: A141076 A092146 A207991 * A143822 A172096 A022893

Adjacent sequences: A120154 A120155 A120156 * A120158 A120159 A120160

KEYWORD

nonn

AUTHOR

Graeme McRae, Jun 10 2006

EXTENSIONS

Name edited by G. C. Greubel, Aug 31 2023

STATUS

approved