A241793 Least number k such that k^n and k^n-1 contain the same number of prime factors (counted with multiplicity) or 0 if no such k exists.

3, 34, 5, 15, 17, 55, 79, 5, 53, 23, 337, 13, 601, 79, 241, 41, 18433, 31, 40961, 89, 3313, 1153

Offset: 1

Author

Derek Orr, May 23 2014

Keywords

• nonn
• more
• hard

Comments

a(23) > 3250.

a(24) = 79. - Jacques Tramu, Sep 16 2018

100000 < a(23) <= 286721. - Jon E. Schoenfield, Sep 25 2018

Examples

			2^1 (2) and 2^1-1 (1) do not have the same number of prime factors. 3^1 (3) and 3^1-1 (2) have the same number of prime factors. Thus a(1) = 3.
		

Crossrefs

Cf. A001222 (bigomega), A242786.

Programs

PARI

a(n)=for(k=2,oo,if(bigomega(k^n)==bigomega(k^n-1),return(k)));

Extensions

a(17) and a(19) corrected by Jacques Tramu, Sep 16 2018