OFFSET
1,1
COMMENTS
Definition: For positive integers b (as base) and n, the positive integer (allowing initial 0's) a(n) is expomorphic relative to base b (here 6) if a(n) has exactly n decimal digits and if b^a(n) == a(n) (mod 10^n) or, equivalently, b^a(n) ends in a(n). [See Crux Mathematicorum link.]
LINKS
Charles W. Trigg, Problem 559, Crux Mathematicorum, page 192, Vol. 7, Jun. 81.
EXAMPLE
6^6 = 46656 ends in 6, so 6 is a term.
6^56 = ...656 ends in 56, so 56 is another term.
MATHEMATICA
Select[Range[10^6], PowerMod[6, #, 10^(1 + Floor@ Log10[#])] == # &] (* Michael De Vlieger, Apr 13 2021 *)
PROG
(PARI) is(n)=my(m=10^#digits(n)); Mod(6, m)^n==n \\ Charles R Greathouse IV, Aug 10 2017
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Bernard Schott, Aug 10 2017
EXTENSIONS
a(6)-a(9) from Charles R Greathouse IV, Aug 10 2017
a(10)-a(13) from Chai Wah Wu, Apr 13 2021
STATUS
approved