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A117196
Prime numbers p such that the decimal expansion of p/pi(p) has only prime digits.
0
2, 11, 19, 23, 71, 863, 3989
OFFSET
1,1
COMMENTS
a(8) > 10^7, if it exists. - Amiram Eldar, May 08 2024
EXAMPLE
71 is in the sequence because it is the 20th prime (pi(71)=20) and the decimal expansion of 71/20 = 3.55 has only prime digits.
MATHEMATICA
q[r_] := AllTrue[RealDigits[r][[1]] // Flatten, PrimeQ]; With[{m = 10000}, p = Prime[Range[m]]; p[[Position[p/Range[m], _?q, Heads -> False] // Flatten]]] (* Amiram Eldar, May 08 2024 *)
CROSSREFS
Cf. A000720.
Sequence in context: A038930 A019375 A078784 * A304811 A064739 A112860
KEYWORD
nonn,base,more
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 21 2006
STATUS
approved