OFFSET
1,1
COMMENTS
Sequence A066509 is a subsequence.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..10000
Daniel C. Mayer, Define an "m-triple" to consist of three consecutive squarefree positive integers, each with exactly m prime divisors, Number Theory group on LinkedIn.com
EXAMPLE
The two squarefree numbers following a(1)=1309=7*11*17 are 1310=2*5*131 and 1311=3*19*23, all three have 3 prime divisors.
The same is true for a(2)=1442, 1443 and the next squarefree number which is 1446.
Further examples are provided by the first "sphenic triples" (1309, 1310, 1311), (1885, 1886, 1887) and (2013, 2014, 2015).
MATHEMATICA
Transpose[Select[Partition[Select[Range[10000], SquareFreeQ], 3, 1], Union[ PrimeNu[ #]] == {3}&]][[1]] (* Harvey P. Dale, Apr 29 2016 *)
PROG
(PARI) (back(n)=for(i=1, 2, until(issquarefree(n--), )); n); for(n=1, 9999, issquarefree(n)||next; ndk==ndm&&omega(n)==ndm&&ndk==3&&print1(back(n)", "); ndk=ndm; ndm=omega(n))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, May 18 2014
EXTENSIONS
Minor edit by Hans Havermann, Aug 19 2014
STATUS
approved