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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A254715 Number of n-digit semiprimes with semiprime digits (4, 6, 9). 1
 3, 4, 8, 18, 55, 137, 415, 941, 2854, 7743, 21959, 61545, 175817, 496688 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..14. FORMULA a(n) = number of n-digit terms in A107342. EXAMPLE a(1) = 3 because there are 3 one-digit semiprimes with semiprime digits: 4,6,9. a(2) = 4 because there are 4 two-digit relevant semiprimes: 46,49,69,94. a(3) = 8 because there are 8 three-digit relevant semiprimes: 446,466,469,649,669,694,699,949. CROSSREFS Cf. A107342. Sequence in context: A183494 A107429 A061273 * A107328 A065034 A332707 Adjacent sequences: A254712 A254713 A254714 * A254716 A254717 A254718 KEYWORD nonn,base AUTHOR Zak Seidov, Feb 06 2015 STATUS approved

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.

Last modified March 2 05:08 EST 2024. Contains 370460 sequences. (Running on oeis4.)