|
%I #5 Feb 08 2015 07:18:52
%S 3,4,8,18,55,137,415,941,2854,7743,21959,61545,175817,496688
%N Number of n-digit semiprimes with semiprime digits (4, 6, 9).
%F a(n) = number of n-digit terms in A107342.
%e a(1) = 3 because there are 3 one-digit semiprimes with semiprime digits: 4,6,9.
%e a(2) = 4 because there are 4 two-digit relevant semiprimes: 46,49,69,94.
%e a(3) = 8 because there are 8 three-digit relevant semiprimes: 446,466,469,649,669,694,699,949.
%Y Cf. A107342.
%K nonn,base
%O 1,1
%A _Zak Seidov_, Feb 06 2015
|
