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A120153
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a(n) = 7 + floor((2 + Sum_{j=1..n-1} a(j))/3).
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1
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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
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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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 *)
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PROG
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(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) >;
(SageMath)
@CachedFunction
def A120153(n): return 7 + (2 + sum(A120153(k) for k in range(1, n)))//3
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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