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A231816
a(n) = the smallest squarefree number (A005117) with n prime factors in a 2p-1 progression.
3
2, 6, 30, 351137972965951, 8596208716179446431, 698211042943963834650959743951, 744014385572130806167897354113929551, 901203402294977554329263775346819632824908852456695769189267773301
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
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
Cf. A057330 (first prime for such numbers that has n factors).
Sequence in context: A153046 A088260 A232171 * A058028 A216834 A287592
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Nov 13 2013
STATUS
approved