OFFSET
1,1
COMMENTS
Here the 'subscript' of an emirp is the index of it over all the primes, not over the emirps (otherwise we would get {A006567(A006567(n))} sorted). - Jianing Song, Oct 29 2019
LINKS
Metin Sariyar, Table of n, a(n) for n = 1..10000
Chris K. Caldwell and G. L. Honaker, Jr., Prime curio for 157
EXAMPLE
157 is a term because 157, 751, pi(157) = 37 and 73 are all primes.
MATHEMATICA
Do[y=IntegerReverse; z=PrimeQ; k=PrimePi[n]; a=y[n]; b=y[k]; If[!a==n&&!b==k&&z[a]&&z[b]&&z[n]&&z[k], Print[n]], {n, 1, 10^5}]
PROG
(PARI) is_emirps(n) = my(r=eval(concat(Vecrev(Str(n))))); isprime(r)&&r!=n&&isprime(n); \\ A006567
isok(n) = is_emirps(n) && is_emirps(primepi(n)); \\ Michel Marcus, Oct 14 2019
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Metin Sariyar, Oct 09 2019
STATUS
approved