OFFSET
1,7
FORMULA
EXAMPLE
a(6) = 0 since 17 is adjacent to 19 (exponent of 7th Mersenne prime).
a(7) = 2 since 23 and 29 are between 19 and 31 (exponent of 8th Mersenne prime).
a(8) = 6 since 37, 41, 43, 47, 53 and 59 are between 31 and 61 (exponent of 9th Mersenne prime).
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jani Melik, Mar 08 2009, Mar 10 2009
EXTENSIONS
a(34)-a(47) from Amiram Eldar, Jun 11 2024
STATUS
approved