Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #22 Jun 22 2018 21:29:17
%S 1,3,9,11,33,99,121,363
%N Powers of 3 written in base 26. (Next term contains a non-decimal digit.)
%C Aliquot divisors of 1089. - _Omar E. Pol_, Jun 10 2014
%C The above comment refers to the first 8 terms only. The next term would contain a digit 18, commonly coded as I, if A, B, ... are used for digits > 9. But this does not mean that the sequence is finite. Many other encodings of digits > 9 are conceivable (e.g., using 000, 100, 110, ..., 250 for digits 0, 10, 11, ..., 25). - _M. F. Hasler_, Jun 22 2018
%t Select[Divisors[1089], # < 1089 &] (* _Wesley Ivan Hurt_, Jun 13 2014 *)
%o (PARI) fordiv(1089, d, (d<1089) && print1(d, ", ")) \\ _Michel Marcus_, Jun 14 2014
%o (PARI) divisors(1089)[^-1] \\ _M. F. Hasler_, Jun 22 2018
%o (PARI) apply( A004668(n,b=26,m=3)=fromdigits(digits(m^n,b)), [0..8]) \\ This implements one possible continuation of the sequence beyond n = 7: write digits in decimal and carry over (so 363*3 = 9I9[26] -> 9*100 + 18*10 + 9 = 1089). - _M. F. Hasler_, Jun 22 2018
%Y Cf. A000244, A004656, A004658, A004659, ..., A004667: powers of 3 in base 10, 2, 4, 5, ..., 13.
%Y Cf. A000079, A004643, ..., A004655: powers of 2 written in base 10, 4, 5, ..., 16.
%K nonn,base
%O 0,2
%A _N. J. A. Sloane_, Dec 11 1996