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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

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Last modified May 21 11:28 EDT 2022. Contains 353908 sequences. (Running on oeis4.)