The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A140745

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

#9 by Joerg Arndt at Tue Aug 10 03:33:00 EDT 2021

STATUS

editing

approved

#8 by Joerg Arndt at Tue Aug 10 03:32:39 EDT 2021

NAME

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

STATUS

reviewed

editing

#7 by Hugo Pfoertner at Tue Aug 10 02:42:50 EDT 2021

STATUS

proposed

reviewed

#6 by Michel Marcus at Tue Aug 10 01:54:35 EDT 2021

STATUS

editing

proposed

#5 by Michel Marcus at Tue Aug 10 01:54:31 EDT 2021

CROSSREFS

Cf. A000225, A001222, A046051, A136033.

STATUS

proposed

editing

#4 by Jinyuan Wang at Tue Aug 10 01:31:50 EDT 2021

STATUS

editing

proposed

#3 by Jinyuan Wang at Tue Aug 10 01:18:07 EDT 2021

NAME

Smallest prime p such that p-th Mersenne number A000225(p) = M_p = 2^p - 1 has prime decomposition into exactly n prime factors (counted with multiplicity).

PROG

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

CROSSREFS

Cf. A000225, A046051, A136033.

KEYWORD

more,nonn

nonn,more

STATUS

approved

editing

#2 by Russ Cox at Sat Mar 31 10:26:07 EDT 2012

AUTHOR

_Lekraj Beedassy (blekraj(AT)yahoo.com), _, Jul 12 2008

Discussion

Sat Mar 31

10:26

OEIS Server: https://oeis.org/edit/global/489

#1 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009

NAME

Smallest prime p such that p-th Mersenne number A000225(p) = M_p = 2^p - 1 has prime decomposition into exactly n factors.

DATA

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.

KEYWORD

more,nonn

AUTHOR

Lekraj Beedassy (blekraj(AT)yahoo.com), Jul 12 2008

STATUS

approved