OFFSET
1,1
COMMENTS
The largest known sphenic number is a term of this sequence.
a(n) == 3 (mod 4) for n >= 1.
LINKS
Wikipedia, Sphenic number (lists the largest known sphenic number)
Wikipedia, Mersenne prime
EXAMPLE
a(1) = 651, since 651 = 3*7*31.
a(2) = 2667, since 2667 = 3*7*127.
a(3) = 11811, since 11811 = 3*31*127.
MATHEMATICA
M = 2^MersennePrimeExponent[Range[12]] - 1; Take[ Union[ Times @@@ Subsets[ M, {3}]], 50]
CROSSREFS
KEYWORD
nonn
AUTHOR
Timothy L. Tiffin, Jul 06 2021
STATUS
approved