OFFSET
1,1
COMMENTS
Smallest squarefree numbers with n >= 2 prime divisors of the form p_1 * p_2 * … * p_n, where p_1 < p_2 < … < p_k = primes with p_k = 2 * p_(k-1) - 1.
Subsequence of A231814.
LINKS
Jaroslav Krizek, Table of n, a(n) for n = 1..15
EXAMPLE
8596208716179446431 = 1531*3061*6121*12241*24481, where 3061 = 2*1531 - 1, 6121 = 2*3061 - 1, 12241 = 2*6121 - 1, 24481 = 2*12241 - 1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Nov 13 2013
STATUS
approved