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A224904
Primes p such that the decimal expansion of p^5 ends in p.
1
2, 3, 5, 7, 43, 193, 251, 307, 443, 499, 557, 751, 1249, 1693, 3307, 4999, 5443, 5807, 7057, 7499, 20807, 22943, 31249, 49999, 52057, 54193, 56249, 79193, 97943, 281249, 672943, 4218751, 4999999, 5422943, 8281249, 8704193, 17077057, 74218751, 407922943
OFFSET
1,1
COMMENTS
Subsequence of A068407. - Giovanni Resta, Jul 25 2013
LINKS
EXAMPLE
193 is a prime and 193^5=267785184193 ends in 193, hence 193 is in the sequence.
MAPLE
with(numtheory):with(StringTools):KD := proc() local a, b, d, e, f; a:= ithprime(n); b:= a^5; d:=length(a); e:=floor(b/(10^d))*10^d; f:=b-e; if a=f then RETURN (a) fi:end:seq(KD(), n=1..500000);
MATHEMATICA
d[n_] := Block[{x}, Select[x /. List@ ToRules@ Reduce[x^5 == x, {x}, Modulus -> 10^n], # > 10^(n-1) && PrimeQ@# &]]; Union @@ d /@ Range@ 9 (* Giovanni Resta, Jul 25 2013 *)
PROG
(PARI) is(n)=isprime(n) && Mod(n, 10^#digits(n))^5==n \\ Charles R Greathouse IV, Jul 26 2013
CROSSREFS
Cf. A068407.
Sequence in context: A279954 A120804 A092066 * A028981 A223035 A096843
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, Jul 25 2013
EXTENSIONS
a(35)-a(39) from Giovanni Resta, Jul 25 2013
STATUS
approved