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A128972 n^3 - 1 divided by its largest cube divisor. 2
7, 26, 63, 124, 215, 342, 511, 91, 37, 1330, 1727, 2196, 2743, 3374, 4095, 614, 17, 254, 7999, 9260, 10647, 12166, 13823, 1953, 17575, 19682, 813, 24388, 26999, 29790, 32767, 4492, 39303, 42874, 46655, 1876, 54871, 59318, 63999, 8615, 74087, 79506 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

In other words, cubefree part of n^3-1, or cubefree kernel of n^3-1. Cube analog of A068310.

LINKS

Robert Israel, Table of n, a(n) for n = 2..10000

FORMULA

a(n) = A062378(A068601(n)) = A062378(n^3-1).

EXAMPLE

a(9) = (9^3-1)/8 = (2^3 * 7 * 13)/(2^3) = 728/8 = 91.

a(10) = (10^3-1)/27 = (3^3 * 37)/(3^3) = 999/27 = 37.

a(18) = (18^3-1)/343 = (7^3 * 17)/(7^3) = 5831/343 = 17.

MAPLE

a:= n -> mul(f[1]^(f[2] mod 3), f = ifactors(n^3-1)[2]):

seq(a(n), n=2..100); # Robert Israel, Sep 24 2014

CROSSREFS

Cf. A002350, A004709, A007948, A062378, A067872, A033314, A068310.

Sequence in context: A211645 A171340 A046433 * A135300 A024001 A068601

Adjacent sequences:  A128969 A128970 A128971 * A128973 A128974 A128975

KEYWORD

easy,nonn

AUTHOR

Jonathan Vos Post, Apr 28 2007

EXTENSIONS

More terms from Carl R. White, Nov 09 2010

STATUS

approved

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Last modified January 26 01:48 EST 2020. Contains 331270 sequences. (Running on oeis4.)