A232068 Least k such that prime(n) + 2^(k+L) is a prime, where L is the length of binary representation of prime(n): L = A070939(A000040(n)). a(n)=-1 if no such k exists.

0, 0, 1, 1, 0, 8, 1, 2, 0, 7, 0, 5, 0, 203, 1, 3, 2, 3, 0, 3, 3, 0, 2, 1, 0, 1, 2, 7, 0, 1, 1, 5, 2, 1, 8, 2, 0, 501, 3, 1, 8, 3, 0, 1, 2, 0, 0, 1, 22, 3, 1, 4, 5, 0, 2, 4, 11, 1, 6, 1, 2, 5, 0, 3, 0, 7, 1, 0, 1, 18, 8, 3, 13, 5, 6, 2, 3, 34, 1, 2, 3, 4, 19, 5, 6, 4, 1

Offset

2,6

Comments

Prime(n) is in A065047 if and only if a(n)=0.

Links

Table of n, a(n) for n=2..88.

Crossrefs

Cf. A000040, A070939, A065047, A094076.

Sequence in context: A254460 A198830 A254244 * A271547 A010154 A109011

Adjacent sequences: A232065 A232066 A232067 * A232069 A232070 A232071

Keyword

nonn,base,less

Author

Alex Ratushnyak, Nov 17 2013

Status

approved