cp's OEIS Frontend

A261970 Numbers whose base-b expansions, for both b=3 and b=4, include no digits other than 0 and b-1.

%I A261970 #51 Oct 13 2015 14:05:31
%S A261970 0,60,240,13308,52992,53052,53196,3195132,3208140,3346188,12795648,
%T A261970 12795900,871563264,871563312,871563456,871576368,871576380,871576524,
%U A261970 871615728,871616268,871616448,1072939776,1072939788,1072939824,3225157884,3472949196,3473670912
%N A261970 Numbers whose base-b expansions, for both b=3 and b=4, include no digits other than 0 and b-1.
%H A261970 Paul Tek, <a href="/A261970/b261970.txt">Table of n, a(n) for n = 1..10000</a>
%H A261970 Paul Tek, <a href="/A261970/a261970.txt">PARI program for this sequence</a>
%e A261970 60 is 2020 in base 3 and 330 in base 4; it uses the largest digits in the two bases (including 0's) and is therefore a term.
%e A261970 Similarly 240 is 22220 in base 3 and 3300 in base 4 so it is also a term.
%o A261970 (PARI) isokb(n, b) = {if (!n, return (1)); my(d = digits(n, b)); (#vecsort(d,,8)==2) && (vecmin(d) == 0) && (vecmax(d) == b - 1);}
%o A261970 isok(n) = isokb(n, 3) && isokb(n, 4); \\ _Michel Marcus_, Sep 22 2015
%Y A261970 Cf. A258981, A262958.
%K A261970 nonn,base
%O A261970 1,2
%A A261970 _Robin Powell_, Sep 21 2015
%E A261970 More terms from _Alois P. Heinz_, Sep 21 2015