A156756 Primes not containing exactly two odd digits.

2, 3, 5, 7, 23, 29, 41, 43, 47, 61, 67, 83, 89, 113, 131, 137, 139, 151, 157, 173, 179, 191, 193, 197, 199, 223, 227, 229, 241, 263, 269, 281, 283, 311, 313, 317, 331, 337, 353, 359, 373, 379, 397, 401, 409, 421, 443, 449, 461, 463, 467, 487, 557, 571, 577, 593

Offset: 1

Author

Juri-Stepan Gerasimov, Feb 15 2009

Keywords

• nonn
• base

Comments

Odd digits are 1, 3, 5, 7 or 9.

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..50000

Crossrefs

Cf. A104638, A119450.

Programs

Mathematica

checkQ[n_] := Module[{d = IntegerDigits[n]}, Length[Select[d, OddQ]] != 2]; Select[Prime[Range[200]], checkQ] (* T. D. Noe, Jun 06 2012 *)

PARI

is(n)=#select(d->d%2,digits(n))!=2 && isprime(n) \\ Charles R Greathouse IV, Apr 08 2016

Formula

a(n) ~ n log n. On the Riemann hypothesis, a(n) = ali(n) + O(n^k log n) where ali is the inverse logarithmic integral and k = log 5/log 10 = 0.69897.... - Charles R Greathouse IV, Apr 08 2016

Extensions

183 replaced by 283 - R. J. Mathar, Feb 20 2009

Definition clarified by Jonathan Sondow, Jun 06 2012