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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A118212 Numbers n such that the reversal of all five numbers n^1, n^2, n^3 n^4 and n^5 are primes. 4
3244, 32440, 324400, 324886, 1109311, 1979137, 3244000, 3248860, 10212316, 10255493, 10282339, 10306511, 10503781, 10573126, 10657861, 10692107, 11093110, 11145841, 11171452, 19791370, 19855967, 19875058, 19912073 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This sequence is infinite because if n is in the sequence then for all natural numbers m, 10^m*n is in the sequence.

Contribution from Farideh Firoozbakht, Sep 29 2009: (Start)

110218462 is the smallest term n such that the reversal of n^6 is also prime.

A165698 is a subsequence of this sequence such that for each term n reversal(n^6)

is also prime. (End)

LINKS

Table of n, a(n) for n=1..23.

EXAMPLE

3244 is in the sequence because reversal(3244^k) for k=1,2,...,5

are respectively 4423, 63532501, 48705383143, 692349908447011,

and 422250654361652953 and these five numbers are primes.

MATHEMATICA

Do[If[PrimeQ[FromDigits[Reverse[IntegerDigits[n]]]] && PrimeQ[FromDigits[Reverse[IntegerDigits[n^2]]]] && PrimeQ [FromDigits[Reverse[IntegerDigits[n^3]]]] && PrimeQ[FromDigits [Reverse[IntegerDigits[n^4]]]] && PrimeQ[FromDigits[Reverse [IntegerDigits[n^5]]]], Print[n]], {n, 32000000}]

Select[Range[20000000], And@@PrimeQ[FromDigits[Reverse[ IntegerDigits[ #]]]&/@ (#^Range[5])]&] (* Harvey P. Dale, Jan 17 2014 *)

CROSSREFS

Cf. A118213.

Cf. A165698. [From Farideh Firoozbakht, Sep 29 2009]

Sequence in context: A252611 A185465 A254974 * A233750 A252014 A247725

Adjacent sequences:  A118209 A118210 A118211 * A118213 A118214 A118215

KEYWORD

base,easy,nonn

AUTHOR

Farideh Firoozbakht, Apr 21 2006

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 15 05:43 EDT 2019. Contains 328026 sequences. (Running on oeis4.)