login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A029971 Palindromic primes in base 3. 9
2, 13, 23, 151, 173, 233, 757, 937, 1093, 1249, 1429, 1487, 1667, 1733, 1823, 1913, 1979, 2069, 8389, 9103, 10111, 12301, 14951, 16673, 16871, 18593, 60103, 60913, 61507, 63127, 69697, 73243, 78979, 80599, 82003, 82813, 83407, 85027 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Intersection of A000040 and A014190. - Michel Marcus, Aug 19 2015

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..3004

P. De Geest, World!Of Palindromic Primes

MAPLE

N:= 14: # to get all terms < 3^N

Res:= 2:

digrev:=proc(n) local L;

  L:= convert(n, base, 3);

  add(L[-i]*3^(i-1), i=1..nops(L))

end proc;

for d from 2 to N do

  if d::even then

    m:= d/2;

    Res:= Res, op(select(isprime, [seq](n*3^m + digrev(n), n=3^(m-1)..3^m-1)));

  else

    m:= (d-1)/2;

    Res:= Res, op(select(isprime, [seq](seq(n*3^(m+1)+y*3^m+digrev(n),

      y=0..2), n=3^(m-1)..3^m-1)));

  fi

od:

Res; # Robert Israel, Aug 19 2015

MATHEMATICA

Do[s = RealDigits[n, 3][[1]]; If[PrimeQ[n], If[FromDigits[s] == FromDigits[Reverse[s]], Print[n]]], {n, 1, 8500}]

Select[Prime[Range[8300]], Reverse[x = IntegerDigits[#, 3]] == x &] (* Jayanta Basu, Jun 23 2013 *)

PROG

(PARI) lista(nn) = forprime(p=2, nn, if ((d=digits(p, 3)) && (Vecrev(d)==d), print1(p, ", "))); \\ Michel Marcus, Aug 19 2015

CROSSREFS

Cf. A117698 (in base 3), A014190.

Sequence in context: A093301 A079397 A118524 * A243619 A243620 A090526

Adjacent sequences:  A029968 A029969 A029970 * A029972 A029973 A029974

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 23 02:46 EDT 2017. Contains 286909 sequences.