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

 

Logo


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.

License Agreements, Terms of Use, Privacy Policy. .

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