OFFSET
1,2
COMMENTS
All terms are of the form 3*m + 1 for some m >= 0.
The first differences appear to contain only powers of 3 and to be weakly increasing.
Run lengths in first differences appear to be regular and suggest a simple procedure to generate the sequence.
LINKS
Rémy Sigrist, Table of n, a(n) for n = 1..10000
Rémy Sigrist, Ternary plot of the terms < 3^10 (blue squares correspond to 1's and red squares to 2's)
EXAMPLE
The ternary representation of 4^4 ("100111") ends with that of 4 ("11"), so 4 is a term.
MATHEMATICA
Select[Range[2100], Take[IntegerDigits[#^#, 3], -IntegerLength[#, 3]] == IntegerDigits[ #, 3]&] (* Harvey P. Dale, Feb 13 2022 *)
PROG
(PARI) is(n, base=3) = Mod(n, base^#digits(n, base))^n==n
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Oct 11 2020
STATUS
approved