The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A096175 Numbers k such that k^3-1 is an odd semiprime. 9

%I

%S 6,8,12,14,20,24,38,54,62,80,90,110,138,150,164,168,192,194,272,278,

%T 314,332,348,398,402,434,500,572,642,644,720,728,762,798,812,860,864,

%U 878,920,992,1020,1022,1070,1092,1098,1118,1130,1182,1202,1230,1260,1308

%N Numbers k such that k^3-1 is an odd semiprime.

%H Hugo Pfoertner, <a href="/A096175/b096175.txt">Table of n, a(n) for n = 1..10000</a>

%H Dario A. Alpern, <a href="http://www.alpertron.com.ar/ECM.HTM">Factorization using the Elliptic Curve Method</a>

%e a(1)=6 because 6^3 - 1 = 216 - 1 = 215 = 5*43.

%o (PARI)

%o forstep (k=2,1310,2,if(bigomega(k^3-1)==2,print1(k,", ")))

%o \\ _Hugo Pfoertner_, Nov 28 2017

%Y Cf. A096173: k^3+1 is an odd semiprime; A081257: largest prime factor of k^3-1; A096176 (k^3-1)/(k-1) is prime; A046315.

%K nonn

%O 1,1

%A _Hugo Pfoertner_, Jun 22 2004

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified January 24 07:18 EST 2020. Contains 331189 sequences. (Running on oeis4.)