OFFSET
1,1
COMMENTS
There are 68 such numbers less than one million; a(68) = 988849.
LINKS
Christian N. K. Anderson, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 4^2 + 6^2 + 9^2 = 133.
MATHEMATICA
Accumulate[Select[Range[200], PrimeOmega[#]==2&]^2] (* Harvey P. Dale, Mar 13 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Kevin L. Schwartz and Christian N. K. Anderson, Mar 22 2013
STATUS
approved