A155048 Primes p such that number of prime digits of prime(p) = number of nonprime digits of prime(p).

7, 11, 17, 19, 23, 191, 199, 211, 227, 251, 277, 281, 311, 337, 347, 353, 359, 373, 383, 389, 397, 401, 409, 419, 439, 463, 467, 479, 523, 547, 557, 569, 571, 577, 593, 599, 613, 619, 641, 643, 653, 659, 673, 677, 683, 701, 709, 743, 751, 757, 769, 787, 809

Offset

1,1

Comments

Prime digits are 2, 3, 5 or 7, nonprime digit are 0, 1, 4, 6, 8 or 9.

Links

Table of n, a(n) for n=1..53.

Prog

(PARI) f(n) = #select(isprime, digits(prime(n))); \\ A109066
isok(p) = my(nbp=f(prime(p))); isprime(p) && (2*f(p) == #digits(prime(p)));  \\ Michel Marcus, Feb 18 2021

Crossrefs

Cf. A000040, A109066, A141468.

Sequence in context: A078497 A274505 A256567 * A296926 A063639 A230223

Adjacent sequences: A155045 A155046 A155047 * A155049 A155050 A155051

Keyword

nonn,base,less

Author

Juri-Stepan Gerasimov, Jan 19 2009

Extensions

Corrected (17 and 479 inserted) by R. J. Mathar, May 05 2010

Status

approved