A235376 Positions of 9's in A235354.

58, 167, 244, 300, 310, 326, 348, 361, 380, 394, 422, 493, 520, 525, 560, 574, 677, 826, 877, 935, 938, 1010, 1049, 1116, 1168, 1201, 1210, 1212, 1334, 1346, 1382, 1411, 1433, 1585, 1591, 1640, 1683, 1750, 1790, 1796, 1805, 1848, 1858, 1891, 1997, 2032, 2114

Offset: 1

Author

Vladimir Shevelev and Peter J. C. Moses, Jan 08 2014

Keywords

• nonn
• base

Comments

If prime(a(n)) is written in base k, 2<=k<=9, and the k-representation is read in decimal, then it will be a prime only for k=9.

Crossrefs

Cf. A000040, A235354.

Programs

PARI

isok(n) = {my(p = prime(n)); for (b = 2, 8, if (isprime(subst(Pol(digits(p, b)), x, 10)), return(0));); isprime(subst(Pol(digits(p, 9)), x, 10));} \\ Michel Marcus, Jan 18 2014