|
Search: id:A099078
|
|
|
| A099078 |
|
Numbers n such that pi(n).pi(n-1) ... pi(3).pi(2) is prime (dot between numbers means concatenation). |
|
+0
4
|
| |
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Number of digits of primes corresponding to the five known terms of this sequence are respectively 4,21,67,605,1633.
|
|
LINKS
|
C. Rivera, ,Primes by Listing, The Prime Puzzles & Problems connection.
Eric Weisstein ,A Section of The World of Mathematics
|
|
EXAMPLE
|
5 is in the sequence because pi(5).pi(4).pi(3).pi(2)=3221 is prime.
|
|
MATHEMATICA
|
s = ""; Do[s = ToString[PrimePi[n]] <> s; k = ToExpression[s]; If[PrimeQ[k], Print[n]], {n, 2, 5235}] (Propper)
|
|
CROSSREFS
|
Cf. A046035, A099077, A099079, A099080.
Sequence in context: A045015 A085101 A082005 this_sequence A049452 A033445 A050533
Adjacent sequences: A099075 A099076 A099077 this_sequence A099079 A099080 A099081
|
|
KEYWORD
|
base,more,nonn
|
|
AUTHOR
|
Farideh Firoozbakht (f.firoozbakht(AT)math.ui.ac.ir), Oct 23 2004
|
|
EXTENSIONS
|
One more term from Ryan Propper (rpropper(AT)stanford.edu), Aug 30 2005
|
|
|
Search completed in 0.002 seconds
|
