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!)
A163113 Fibonacci numbers containing equal numbers of prime digits and nonprime digits. 0
13, 21, 34, 1597, 2584, 6765, 121393, 514229, 14930352, 24157817, 7778742049, 365435296162, 44945570212853, 184551825793033096366333, 781774079430987230203437, 7896325826131730509282738943634332893686268675876375 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It is obvious that these numbers must contain an even number of digits.

This sequence is probably finite. The equivalent sequences in bases 4, 6, and 8 are probably infinite. - Franklin T. Adams-Watters, Aug 06 2009

LINKS

Table of n, a(n) for n=1..16.

Simon Plouffe, Project Gutenberg

EXAMPLE

24157817 is a Fibonacci number containing equal numbers of prime digits (2,5,7,7) and nonprime digits (4,1,8,1).

MATHEMATICA

pnpQ[n_]:=Module[{idn=IntegerDigits[n], len}, len=Length[idn]; EvenQ[len] && Count[idn, _?PrimeQ]==len/2]; Select[Fibonacci[Range[250]], pnpQ] (* Harvey P. Dale, May 01 2012 *)

PROG

(PARI) (digits(n, b=10)=local(r); r=[]; while(n>0, r=concat([n%b], r); n\=b); r); for(n=1, 500, v=digits(fibonacci(n)); np=sum(i=1, #v, isprime(v[i])); if(#v==2*np, print1(fibonacci(n)", ")))

CROSSREFS

Cf. A000045.

Sequence in context: A164451 A164432 A034292 * A164496 A164459 A164453

Adjacent sequences:  A163110 A163111 A163112 * A163114 A163115 A163116

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Jul 21 2009

EXTENSIONS

Edited and extended by Franklin T. Adams-Watters, Aug 06 2009

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 October 27 10:47 EDT 2021. Contains 348274 sequences. (Running on oeis4.)