OFFSET
1,1
COMMENTS
The number of distinct prime factors is A001221.
If any following terms exist, they are greater than 10^13.
Eggleton and MacDougall show that there are no more than 59 terms in this sequence.
a(19) <= 7523987244435061. - Donovan Johnson, Jul 08 2013
LINKS
Roger B. Eggleton and James A. MacDougall, Consecutive integers with equally many principal divisors, Math. Mag. 81 (2008), 235-248.
R. B. Eggleton, J. S. Kimberley, and J. A. MacDougall, Principal divisor ranks of the first trillion positive integers, NOVA: The University of Newcastle’s Digital Research Repository (2009).
EXAMPLE
a(14) < a(13) because the first run of 13 consecutive integers i with A001221(i)=3 is not a maximal run.
CROSSREFS
KEYWORD
nonn,fini
AUTHOR
R. B. Eggleton, Jason Kimberley, and J. A. MacDougall, Apr 12 2011
STATUS
approved