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, 44987, 53017
Offset: 1
Keywords
Examples
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
Programs
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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
Formula
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
a(28)-a(29) from Michael S. Branicky, Jul 03 2025
Comments