OFFSET
1,1
COMMENTS
Also sum of n-th Mersenne prime and the radical of n-th even perfect number.
The binary representation of a(n) has only two zeros, starting with "10" and ending with "01". The sequence begins: 1001, 10101, 1011101, 101111101, 101111111111101,...
FORMULA
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Dec 20 2016
STATUS
approved