A219227 - OEIS

A219227

a(n) is the sum of n addends nested as follows: floor(f(floor(f(...(n)...)))) where f(x) = x^(1/3).

1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 67, 68, 69, 70, 71, 72, 73

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OFFSET

1,2

COMMENTS

Its complement is 8, 28, 66, 128, 220, 348, 518, 519, 737, 1009, 1341, 1739, 2209, 2757, 3389, 4111, 4929, ..., .

LINKS

Table of n, a(n) for n=1..70.

EXAMPLE

For n=8, floor(8^(1/3))=2, and floor(floor(8^(1/3))^(1/3))=1 as do the remaining six terms, so a(8) = 2 + 7*1 = 9.

MATHEMATICA

a[n_] := Plus @@ Rest@ NestList[ Floor[#^(1/3)] &, n, n]; Array[a, 60]

CROSSREFS