The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A156756 Primes not containing exactly two odd digits. 5
 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 (list; graph; refs; listen; history; text; internal format)
 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: A240920 A030144 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 27 21:52 EDT 2020. Contains 334671 sequences. (Running on oeis4.)