0,11

For n even >2 the least prime is of the form (2^n)*(10^k)+1 For n odd >2 the least prime is of the form (2^n)*(10^k)-1 Mersenne-primes are in the sequence with a(n)=0 and n prime

(2^0)*(10^0)+1=2 prime so a(0)=0

(2^1)*(10^0)+1=3 prime so a(1)=0

(2^2)*(10^0)-1=3 prime as (2^2)*(10^0)+1=5 prime so a(2)=0

Sequence in context: A104845 A138731 A020432 this_sequence A032751 A020436 A104947

Adjacent sequences: A102745 A102746 A102747 this_sequence A102749 A102750 A102751

nonn

Pierre CAMI (pierrecami(AT)tele2.fr), Feb 09 2005