A352380 - OEIS

%I #13 Mar 16 2022 03:18:18

%S 9,18,19,23,26,29,69,83,89,143,149,158,159,163,166,169,186,193,196,

%T 199,203,209,219,223,229,233,236,249,253,258,260,263,269,283,286,289,

%U 290,293,298,299,319,323,326,669,683,689,743,759,763,803,809,823,829,833,849,853,859,863,869,883,893,899

%N Numbers k such that no nonzero digit of 3*k divides 3*k.

%e a(1) = 9 and 3*9 = 27 is not divisible by 2 or 7;

%e a(2) = 18 and 3*18 = 54 is not divisible by 5 or 4;

%e a(3) = 19 and 3*19 = 57 is not divisible by 5 or 7;

%e a(4) = 23 and 3*23 = 69 is not divisible by 6 or 9; etc.

%e 31 is not in the sequence as 3*31 = 93 is divisible by 3.

%t q[n_] := AllTrue[IntegerDigits[3*n], # == 0 || !Divisible[3*n, #] &]; Select[Range[900], q] (* _Amiram Eldar_, Mar 14 2022 *)

%o (Python)

%o def ok(n): return not any(3*n%int(d)==0 for d in set(str(3*n)) if d!='0')

%o print([k for k in range(1, 900) if ok(k)]) # _Michael S. Branicky_, Mar 14 2022

%Y Cf. A038772, A352379, A352381, A352382.

%K base,nonn

%O 1,1

%A _Eric Angelini_ and _Carole Dubois_, Mar 14 2022