A044968 - OEIS

%I #18 Jul 26 2023 03:20:40

%S 13,41,43,49,67,125,131,133,149,151,157,203,205,211,229,377,395,401,

%T 403,449,455,457,473,475,481,611,617,619,635,637,643,689,691,697,715,

%U 1133,1187,1205,1211,1213,1349,1367,1373,1375,1421,1427,1429,1445,1447,1453

%N Numbers whose base-3 representation contains no 0's and exactly three 1's.

%H Robert Israel, <a href="/A044968/b044968.txt">Table of n, a(n) for n = 1..10000</a>

%p sort([seq(seq(3^d-1-add(3^j, j=s),s=combinat:-choose([$0..(d-1)],3)),d=3..8)]); # _Robert Israel_, Mar 29 2023

%t Select[Range[1500],DigitCount[#,3,0]==0&&DigitCount[#,3,1]==3&] (* _Harvey P. Dale_, Feb 27 2023 *)

%Y Cf. A007089.

%K nonn,base

%O 1,1

%A _Clark Kimberling_