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!)
A080790 Binary emirps, primes whose binary reversal is a different prime. 5
11, 13, 23, 29, 37, 41, 43, 47, 53, 61, 67, 71, 83, 97, 101, 113, 131, 151, 163, 167, 173, 181, 193, 197, 199, 223, 227, 229, 233, 251, 263, 269, 277, 283, 307, 331, 337, 349, 353, 359, 373, 383, 409, 421, 431, 433, 449, 461, 463, 479, 487, 491, 503, 509, 521 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Members of A074832 that are not in A006995. - Robert Israel, Aug 31 2016

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

EXAMPLE

A000040(10)=29 -> '11101' rev '10111' -> 23=A000040(9), therefore 29 and 23 are terms.

The prime 19 is not a term, as 19 -> '10011' rev '11001' -> 25=5^2; and 7=A074832(3) is not a term because it is a binary palindrome (A006995) and therefore not different.

MAPLE

revdigs:= proc(n) local L; L:= convert(n, base, 2); add(L[-i]*2^(i-1), i=1..nops(L)) end proc:

filter:= proc(t) local r; if not isprime(t) then return false fi;

  r:= revdigs(t); r <> t and isprime(r) end proc:

select(filter, [seq(i, i=3..10000, 2)]); # Robert Israel, Aug 30 2016

CROSSREFS

Cf. A006567, A006995, A074832, A004676, A007088.

Sequence in context: A075519 A019406 A289688 * A066123 A048393 A136058

Adjacent sequences:  A080787 A080788 A080789 * A080791 A080792 A080793

KEYWORD

nonn,base

AUTHOR

Reinhard Zumkeller, Mar 25 2003

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 July 28 17:15 EDT 2021. Contains 346335 sequences. (Running on oeis4.)