The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A092619

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A092619

Numbers with property that number of prime digits is prime.
(history; published version)

#18 by Alois P. Heinz at Wed Feb 08 11:03:34 EST 2023

STATUS

editing

approved

#17 by Alois P. Heinz at Wed Feb 08 11:03:26 EST 2023

MAPLE

# second Maple program:

q:= n-> isprime(nops(select(isprime, convert(n, base, 10)))):

select(q, [$1..500])[]; # Alois P. Heinz, Feb 08 2023

STATUS

proposed

editing

#16 by Chai Wah Wu at Wed Feb 08 10:59:33 EST 2023

STATUS

editing

proposed

#15 by Chai Wah Wu at Wed Feb 08 10:59:11 EST 2023

PROG

(Python)

from itertools import count, islice

from sympy import isprime

def A092619_gen(startvalue=1): # generator of terms >= startvalue

return filter(lambda n:isprime(sum(1 for d in str(n) if d in {'2', '3', '5', '7'})), count(max(startvalue, 1)))

A092619_list = list(islice(A092619_gen(), 20)) # Chai Wah Wu, Feb 08 2023

STATUS

approved

editing

#14 by Michael De Vlieger at Fri Jan 21 23:30:01 EST 2022

STATUS

proposed

approved

#13 by Jon E. Schoenfield at Fri Jan 21 23:10:23 EST 2022

STATUS

editing

proposed

#12 by Jon E. Schoenfield at Fri Jan 21 23:09:58 EST 2022

COMMENTS

Upper relative density in the primes is 1; lower relative density in the primes is 0. [From _- _Charles R Greathouse IV_, Nov 14 2010]

EXAMPLE

22 has two prime digits and their number 2 is prime, so 22 is a term.

222 has three prime digits and their number 3 is prime, so 222 is a term.

STATUS

approved

editing

#11 by Charles R Greathouse IV at Thu Nov 21 12:48:17 EST 2013

MATHEMATICA

Select[Range[250], PrimeQ[Count[IntegerDigits[#], _?PrimeQ]]&] (* From _Harvey P. Dale, _, Nov 29 2011 *)

Discussion

Thu Nov 21

12:48

OEIS Server: https://oeis.org/edit/global/2062

#10 by Charles R Greathouse IV at Mon May 13 01:48:21 EDT 2013

COMMENTS

Upper relative density in the primes is 1; lower relative density in the primes is 0. [From _Charles R Greathouse IV, _, Nov 14 2010]

Discussion

Mon May 13

01:48

OEIS Server: https://oeis.org/edit/global/1914

#9 by Russ Cox at Sat Mar 31 14:40:00 EDT 2012

AUTHOR

_Jani Melik (jani_melik(AT)hotmail.com), _, Apr 11 2004

Discussion

Sat Mar 31

14:40

OEIS Server: https://oeis.org/edit/global/936