The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A031974

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A031974

1 repeated prime(n) times.
(history; published version)

#52 by Charles R Greathouse IV at Sun Feb 16 08:32:36 EST 2025

LINKS

Eric Weisstein's World of Mathematics, <a href="httphttps://mathworld.wolfram.com/SmarandacheSequences.html">Smarandache Sequences</a>

Discussion

Sun Feb 16

08:32

OEIS Server: https://oeis.org/edit/global/3014

#51 by Charles R Greathouse IV at Thu Sep 08 08:44:50 EDT 2022

PROG

(MAGMAMagma) [(10^p-1)/9: p in PrimesUpTo(40)]; // Vincenzo Librandi, May 29 2014

Discussion

Thu Sep 08

08:44

OEIS Server: https://oeis.org/edit/global/2944

#50 by Joerg Arndt at Wed Aug 09 02:44:13 EDT 2017

STATUS

reviewed

approved

#49 by Michel Marcus at Wed Aug 09 02:19:55 EDT 2017

STATUS

proposed

reviewed

#48 by Jon E. Schoenfield at Wed Aug 09 00:30:54 EDT 2017

STATUS

editing

proposed

#47 by Jon E. Schoenfield at Wed Aug 09 00:30:49 EDT 2017

FORMULA

a(n) = (10^prime(n) - 1)/9. - Vincenzo Librandi, May 29 2014

MAPLE

f:=n->(10^ithprime(n)-1)/9; [seq(f(n), n=1..20)]; # From __N. J. A. Sloane_, Dec 05 2012

EXTENSIONS

More terms from Erich Friedman.

STATUS

approved

editing

#46 by N. J. A. Sloane at Sat Apr 09 13:06:52 EDT 2016

STATUS

proposed

approved

#45 by Thomas Ordowski at Sat Apr 09 10:38:31 EDT 2016

STATUS

editing

proposed

#44 by Thomas Ordowski at Sat Apr 09 10:36:14 EDT 2016

COMMENTS

If p is a prime and gcd(p,b-1)=1, then (b^p-1)/(b-1) == 1 (mod p); by Fermat's little theorem. For example 1111111 == 1 (mod 7). - Thomas Ordowski, Apr 09 2016

STATUS

approved

editing

#43 by Joerg Arndt at Mon Sep 15 12:35:42 EDT 2014

STATUS

reviewed

approved