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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A054518 Emirpnons (nonprimes whose reversal is a different nonprime). 1
10, 12, 15, 18, 21, 24, 25, 26, 27, 28, 36, 39, 40, 42, 45, 46, 48, 49, 51, 52, 54, 56, 57, 58, 60, 62, 63, 64, 65, 68, 69, 72, 75, 78, 80, 81, 82, 84, 85, 86, 87, 90, 93, 94, 96, 100, 102, 105, 108, 114, 115, 116, 117, 120 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

EXAMPLE

a(1)=12 because 12 is not a prime, neither is 21 and 12<>21

MATHEMATICA

emirpnonQ[n_]:=Module[{idn=IntegerDigits[n], ridn}, ridn=Reverse[idn]; n>9&&ridn!=idn&&!PrimeQ[FromDigits[ridn]]]; With[{nprs=Complement[ Range[ 120], Prime[ Range[PrimePi[120]]]]}, Select[nprs, emirpnonQ]] (* Harvey P. Dale, Feb 05 2012 *)

CROSSREFS

Cf. A006567.

Sequence in context: A030591 A006793 A248715 * A072198 A057485 A162825

Adjacent sequences:  A054515 A054516 A054517 * A054519 A054520 A054521

KEYWORD

base,easy,nonn

AUTHOR

Henry Bottomley, Apr 07 2000

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 March 20 05:34 EDT 2019. Contains 321344 sequences. (Running on oeis4.)