A154524 - OEIS

A154524

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

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

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OFFSET

1,1

COMMENTS

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

LINKS

Table of n, a(n) for n=1..27.

FORMULA

A057825 INTERSECT A000040. - R. J. Mathar, Jan 14 2009

EXAMPLE

7 is in the sequence because it is prime and also lcm(1,2,3,4,5,6,7)-1 = 420-1 = 419 is prime. - Emeric Deutsch, Jan 16 2009

MAPLE

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

CROSSREFS

Cf. A056604, A154525, A154526.

Sequence in context: A002261 A263257 A261456 * A184805 A079131 A179687

Adjacent sequences: A154521 A154522 A154523 * A154525 A154526 A154527

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Jan 11 2009

EXTENSIONS

a(8)-a(17) from Ray Chandler, Jan 16 2009

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

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

STATUS

approved