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A081257 Greatest prime factor of n^3-1. 6
7, 13, 7, 31, 43, 19, 73, 13, 37, 19, 157, 61, 211, 241, 13, 307, 17, 127, 421, 463, 13, 79, 601, 31, 37, 757, 271, 67, 29, 331, 151, 1123, 397, 97, 43, 67, 1483, 223, 547, 1723, 139, 631, 283, 109, 103, 61, 181, 43, 2551, 379, 919, 409, 2971, 79, 103, 3307, 163 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

R. J. Mathar, Table of n, a(n) for n = 2..1000

EXAMPLE

a(7)=19 because 7^3-1=342=2*3*3*19

MAPLE

A081257 := proc(n)

        A006530( n^3-1) ;

end proc: # R. J. Mathar, Jul 18 2015

MATHEMATICA

FactorInteger[#][[-1, 1]]&/@(Range[2, 60]^3-1) (* Harvey P. Dale, Oct 09 2017 *)

PROG

(PARI) a(n)=my(f=factor(n^3-1)); f[#f~, 1] \\ Charles R Greathouse IV, Mar 08 2017

CROSSREFS

Cf. A081256, A081258.

Cf. A096175 n^3-1 is an odd semiprime, A096176 (n^3-1)/(n-1) is prime.

Sequence in context: A103705 A157517 A164929 * A046163 A130770 A158622

Adjacent sequences:  A081254 A081255 A081256 * A081258 A081259 A081260

KEYWORD

easy,nonn

AUTHOR

Jan Fricke (fricke(AT)uni-greifswald.de), Mar 14 2003

EXTENSIONS

More terms from Hugo Pfoertner, Jun 21 2004

STATUS

approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)