A113767 Values of the exponents in A084435.

0, 1, 2, 1, 5, 1, 1, 29, 3, 37, 31, 227, 835, 115, 7615, 6071, 218431

Offset

1,3

Comments

If A084435 ever hits a Sierpinski number, the sequence is finite.

a(18) > 10^5. - Harsh R. Aggarwal, Apr 11 2018

Links

Table of n, a(n) for n=1..17.

Eric Weisstein's World of Mathematics, Sierpinski Number of the Second Kind.

Prog

(PARI) a=2; for(x=1, 16, for(k=0, 1000000, p=2^k*a+1; if(isprime(p), print(k); break)); a=p)

Crossrefs

Cf. A084435, A113334, A121799.

Sequence in context: A323954 A143983 A282988 * A352566 A246964 A157334

Adjacent sequences: A113764 A113765 A113766 * A113768 A113769 A113770

Keyword

nonn,hard,more

Author

Ken Takusagawa, Jan 19 2006

Extensions

a(16)-a(17) from Harsh R. Aggarwal, Apr 11 2018

Status

approved