OFFSET
1,3
LINKS
Yusuke Chishiki, Takeshi Goto, and Yasuo Ohno, On the largest prime divisor of an odd harmonic number, Mathematics of Computation, Vol. 76, No. 259 (2007), pp. 1577-1587.
EXAMPLE
There are 3 harmonic seed numbers whose largest prime factor is A065091(3) = 7 (28, 672 and 30240), thus a(3) = 3.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Mar 31 2017
STATUS
approved