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Revision History for A154524

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A154524

Primes p such that lcm(1,2,3,...,p-2,p-1,p) - 1 is prime.
(history; published version)

#15 by Bruno Berselli at Sat Oct 06 11:46:50 EDT 2018

STATUS

reviewed

approved

#14 by Joerg Arndt at Sat Oct 06 11:46:37 EDT 2018

STATUS

proposed

reviewed

#13 by Michel Marcus at Sat Oct 06 11:12:49 EDT 2018

STATUS

editing

proposed

#12 by Michel Marcus at Sat Oct 06 11:12:43 EDT 2018

EXTENSIONS

a(8)-a(2717) from Ray Chandler, Jan 16 2009

More terms a(18)-a(22) from Emeric Deutsch, Jan 16 2009

STATUS

proposed

editing

Discussion

Sat Oct 06

11:12

Michel Marcus: indeed

#11 by Daniel Suteu at Sat Oct 06 11:09:25 EDT 2018

STATUS

editing

proposed

#10 by Daniel Suteu at Sat Oct 06 11:08:08 EDT 2018

DATA

3, 5, 7, 19, 23, 29, 47, 61, 97, 181, 233, 307, 401, 887, 1021, 1087, 1361, 1481, 2053, 2293, 5407, 5857, 11059, 14281, 27277, 27803, 36497

COMMENTS

a(28) > 42000. - Daniel Suteu, Oct 06 2018

EXTENSIONS

a(23)-a(27) from Daniel Suteu, Oct 06 2018

STATUS

approved

editing

Discussion

Sat Oct 06

11:09

Daniel Suteu: There seems to be a typo in "a(8)-a(27) from Ray Chandler". Perhaps it was meant to say "a(8)-a(17) from Ray Chandler"?

#9 by Alois P. Heinz at Sun Mar 04 16:58:50 EST 2018

STATUS

editing

approved

#8 by Alois P. Heinz at Sun Mar 04 16:58:43 EST 2018

MAPLE

P := proc (n) options operator, arrow: lcmilcm(seq(j, j = 1 .. n)) end proc: a := proc (n) if isprime(n) = true and isprime(P(n)-1) = true then n else end if end proc: seq(a(n), n = 1 .. 3000); # Emeric Deutsch, Jan 16 2009

STATUS

proposed

editing

#7 by Jon E. Schoenfield at Sun Mar 04 16:47:03 EST 2018

STATUS

editing

proposed

#6 by Jon E. Schoenfield at Sun Mar 04 16:47:01 EST 2018

NAME

Primes p such that LCM[lcm(1,2,3,...,p-2,p-1,p] ) - 1 is prime.

FORMULA

A057825 INTERSECT A000040. [From _- _R. J. Mathar_, Jan 14 2009]

EXAMPLE

7 is in the sequence because it is prime and also LCMlcm(1,2,3,4,5,6,7)-1 = 420-1 = 419 is prime. [From _- _Emeric Deutsch_, Jan 16 2009]

MAPLE

P := proc (n) options operator, arrow: lcm(seq(j, j = 1 .. n)) end proc: a := proc (n) if isprime(n) = true and isprime(P(n)-1) = true then n else end if end proc: seq(a(n), n = 1 .. 3000); [From _# _Emeric Deutsch_, Jan 16 2009]

STATUS

approved

editing