A030091 Primes such that p and p^2 have same set of digits.

94583, 100469, 102953, 107251, 110923, 184903, 279863, 285101, 406951, 459521, 493621, 499423, 504821, 684581, 752681, 758141, 758941, 786431, 836291, 843701, 928637, 976513, 980261, 1008947, 1009859, 1024399, 1029647

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base
• nice

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040, A029793.

Programs

Haskell

import Data.List (nub, sort)
import Data.Function (on)
a030091 n = a030091_list !! (n-1)
a030091_list =
   filter (\x -> ((==) `on` (nub . sort . show)) x (x^2)) a000040_list
-- Reinhard Zumkeller, Aug 11 2011

Mathematica

Select[Prime[Range[82000]],Union[IntegerDigits[#]]== Union[ IntegerDigits [#^2]]&] (* Harvey P. Dale, Aug 12 2011 *)

PARI

isA030091(n)=isprime(n)&&Set(Vec(Str(n)))==Set(Vec(Str(n^2))) \\ Charles R Greathouse IV, Jun 28 2011

Formula

Equals A000040 INTERSECTION A029793. - Jonathan Vos Post, Jul 06 2008