|
| |
|
|
A345389
|
|
Primes that are not emirps but whose digit reversal is a power of an emirp.
|
|
0
|
|
|
|
9049, 9631, 125329, 148249, 180289, 1000651, 1027591, 1250023, 1460479, 1674931, 1825891, 1889221, 3989683, 9003703, 9041143, 9049231, 10612219, 14499601, 14663479, 16333459, 18005983, 18428101, 90876631, 98087809, 98873821, 100720513, 100922011, 101274443, 108344311, 121623511, 123736969
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
Table of n, a(n) for n=1..31.
|
|
|
EXAMPLE
|
a(3) = 125329 is a term because it is prime and its reversal 923521 = 31^4 where 31 is an emirp.
|
|
|
MAPLE
|
revdigs:= proc(n) local L, i; L:= convert(n, base, 10); add(L[-i]*10^(i-1), i=1..nops(L)) end proc:
isemirp:= proc(n) local r; if not isprime(n) then return false fi;
r:= revdigs(n); r <> n and isprime(r) end proc:
E:= select(isemirp, [seq(i, i=11..10^5, 2)]):
EP:= map(proc(x) local i; seq(x^i, i=2..floor(log[x](10^10))) end proc, E):
EPR:= map(revdigs, EP):
sort(select(isprime, EPR));
|
|
|
CROSSREFS
|
Cf. A006567, A143260.
Sequence in context: A210179 A161610 A204535 * A202914 A252443 A061135
Adjacent sequences: A345386 A345387 A345388 * A345390 A345391 A345392
|
|
|
KEYWORD
|
nonn,base,look
|
|
|
AUTHOR
|
J. M. Bergot and Robert Israel, Jun 17 2021
|
|
|
STATUS
|
approved
|
| |
|
|
