

A068951


Scan the primes, record digitsum if it is itself prime.


1



2, 3, 5, 7, 2, 5, 11, 5, 7, 11, 7, 13, 11, 17, 2, 5, 5, 11, 13, 7, 13, 11, 17, 11, 13, 17, 19, 7, 11, 13, 7, 11, 17, 11, 13, 5, 7, 11, 7, 13, 11, 17, 13, 19, 19, 5, 13, 7, 11, 17, 11, 13, 17, 19, 17, 13, 19, 17, 23, 7, 13, 11, 13, 17, 13, 17, 17, 13, 19, 13, 19, 17, 23, 17, 11, 13
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


LINKS

Table of n, a(n) for n=1..76.


EXAMPLE

a(13)=5 since the 13th prime is 41 and 4+1=5, which is prime.


MAPLE

dig := X>convert((convert(X, base, 10)), `+`); a := n>`if`(isprime(dig(ithprime(n)))=true, dig(ithprime(n)), printf(""));


CROSSREFS

Cf. A046704.
Sequence in context: A007605 A077765 A078400 * A139752 A238191 A004088
Adjacent sequences: A068948 A068949 A068950 * A068952 A068953 A068954


KEYWORD

easy,nonn,base


AUTHOR

Francois Jooste (phukraut(AT)hotmail.com), Mar 10 2002


STATUS

approved



