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A120153
a(n) = 7 + floor((2 + Sum_{j=1..n-1} a(j))/3).
1
7, 10, 13, 17, 23, 31, 41, 55, 73, 97, 130, 173, 231, 308, 410, 547, 729, 972, 1296, 1728, 2304, 3072, 4096, 5462, 7282, 9710, 12946, 17262, 23016, 30688, 40917, 54556, 72741, 96988, 129318, 172424, 229898, 306531, 408708, 544944
OFFSET
1,1
LINKS
MATHEMATICA
nxt[{t_, a_}]:=Module[{c=Floor[(23+t)/3]}, {t+c, c}]; Rest[Transpose[ NestList[ nxt, {0, 7}, 40]][[2]]] (* Harvey P. Dale, Oct 08 2015 *)
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) >;
A120153:= func< n | g(n, 7, 2) >;
[A120153(n): n in [1..60]]; // G. C. Greubel, Jun 15 2023
(SageMath)
@CachedFunction
def A120153(n): return 7 + (2 + sum(A120153(k) for k in range(1, n)))//3
[A120153(n) for n in range(1, 61)] # G. C. Greubel, Jun 15 2023
CROSSREFS
KEYWORD
nonn
AUTHOR
Graeme McRae, Jun 10 2006
STATUS
approved