OFFSET
1,1
EXAMPLE
2*2-1=3 2*2+1=5, 3 and 5 twin primes so a(1)=2;
2*2*3-1=11 2*2*3+1=13, 11 and 13 twin primes so a(2)=3;
2*2*3*5-1=59 2*2*3*5+1=61, 59 and 61 twin primes so a(3)=5.
MAPLE
isA001359 := proc(n) RETURN(isprime(n) and isprime(n+2)); end: primo := 2 : print(primo); for n from 2 to 20000 do p := ithprime(n); primo := primo*p; if isA001359(2*primo-1) then print(p); fi; od : # R. J. Mathar, Aug 09 2006
PROG
(Magma) [p:p in PrimesUpTo(4000)|IsPrime(2*&*PrimesUpTo(p)-1) and IsPrime(2*&*PrimesUpTo(p)+1)]; // Marius A. Burtea, Mar 25 2019
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Pierre CAMI, May 25 2006
STATUS
approved