login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A254715 Number of n-digit semiprimes with semiprime digits (4, 6, 9). 1

%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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 20 03:03 EDT 2024. Contains 371798 sequences. (Running on oeis4.)