A096175 Numbers k such that k^3-1 is an odd semiprime.

6, 8, 12, 14, 20, 24, 38, 54, 62, 80, 90, 110, 138, 150, 164, 168, 192, 194, 272, 278, 314, 332, 348, 398, 402, 434, 500, 572, 642, 644, 720, 728, 762, 798, 812, 860, 864, 878, 920, 992, 1020, 1022, 1070, 1092, 1098, 1118, 1130, 1182, 1202, 1230, 1260, 1308

Offset: 1

Author

Hugo Pfoertner, Jun 22 2004

Keywords

• nonn

Examples

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

Links

• Hugo Pfoertner, Table of n, a(n) for n = 1..10000
• Dario A. Alpern, Factorization using the Elliptic Curve Method

Crossrefs

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.

Programs

PARI

forstep (k=2,1310,2,if(bigomega(k^3-1)==2,print1(k,", ")))
\\ Hugo Pfoertner, Nov 28 2017