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

1,1

Comments

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

Links

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

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

Mathematica

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

Prog

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

Crossrefs

Cf. A000040.

Sequence in context: A343590 A343591 A323578 * A225659 A068690 A069556

Adjacent sequences: A156753 A156754 A156755 * A156757 A156758 A156759

Keyword

nonn,base

Author

Juri-Stepan Gerasimov, Feb 15 2009

Extensions

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

Definition clarified by Jonathan Sondow, Jun 06 2012

Status

approved