A140745 Smallest prime p such that the Mersenne number A000225(p) = 2^p - 1 has exactly n prime factors (counted with multiplicity).

2, 11, 29, 157, 113, 223, 491, 431, 397

Offset

1,1

References

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 223, pp 63-4, Ellipse Paris 2008.

Links

Table of n, a(n) for n=1..9.

Prog

(PARI) a(n) = forprime(p=2, oo, if(bigomega(2^p-1)==n, return(p))); \\ Jinyuan Wang, Aug 10 2021

Crossrefs

Cf. A000225, A001222, A046051, A136033.

Sequence in context: A220095 A133558 A285812 * A356567 A178629 A062802

Adjacent sequences: A140742 A140743 A140744 * A140746 A140747 A140748

Keyword

nonn,more

Author

Lekraj Beedassy, Jul 12 2008

Status

approved