

A066735


Primes p dividing 1 + the product of the primes less than p.


5




OFFSET

1,1


COMMENTS

No further terms up to prime(216816) = 2999999. Is the sequence finite?  Klaus Brockhaus, Jan 17 2002
From Lévai Gábor (gablevai(AT)vipmail.hu), Nov 23 2004: (Start)
Let p(1)=2, p(2)=3, p(3)=5, ... denote the primes and let E(n) = 1 + p(1) * p(2) * ... * p(n). For k >= 1, list the primes p such that p(n+k)  E(n). For k=1 we get this sequence, for k=2 we get A100465.
For k >= 3 the known results are as follows: if k = 3: no solutions for p < 80000000; if k = 4: 463, 2908123 and no others for p < 80000000; if k = 5: 61, 73 and no others for p < 80000000; if k = 6: 21687203 and no others for p < 80000000; if k = 7: 149, 43951591 and no others for p < 80000000; if k = 8: 31, 131 and no others for p < 80000000; if k = 9: 58691999 and no others for p < 80000000. (End)
No further terms up to 80000000.  Lévai Gábor (gablevai(AT)vipmail.hu), Nov 23 2004


LINKS



EXAMPLE

1 + Product of the primes < 19 = 1 + 2*3*5*7*11*13*17 = 510511 = 19*26869; so 19 is a term of the sequence.


MATHEMATICA

p = 2; Do[q = Prime[n]; If[ IntegerQ[(p + 1)/q], Print[q]]; p = p*q, {n, 2, 86120} ]


PROG

(PARI) a066735(m) =local(k, p); k=1; forprime(p=2, m, if((k+1)%p==0, print1(p, ", ")); k=k*p)


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



