OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
The sixth semiprime = 15 = '1111' with four 1's, so 15 is a term.
MATHEMATICA
binWt[n_] := DigitCount[n, 2, 1]; seqQ[n_] := PrimeOmega[n] == 2 && PrimeOmega[binWt[n]] == 2; Select[Range[500], seqQ] (* Amiram Eldar, Dec 14 2019 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jason Earls, Jul 09 2003
STATUS
approved