A061825 - OEIS

%I #19 Nov 03 2019 01:44:10

%S 7,35,77,91,119,133,175,315,357,371,399,511,539,553,595,735,777,791,

%T 917,931,959,973,1113,1155,1197,1337,1351,1379,1393,1519,1533,1575,

%U 1715,1757,1771,1799,1911,1939,1953,1995,3115,3157,3171,3199,3311,3339

%N Multiples of 7 containing only odd digits.

%H Robert Israel, <a href="/A061825/b061825.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.

%e 315 = 7*45 is a term as it contains only odd digits.

%p R:= NULL:

%p for d from 1 to 4 do

%p   for n from 5^d to 2*5^d-1 do

%p     L:= map(t -> 2*t+1,convert(n,base,5)[1..d]);

%p     x:= add(L[i]*10^(i-1),i=1..nops(L));

%p     if x mod 7 = 0 then

%p       R:= R, x;

%p     fi;

%p od od:

%p R; # _Robert Israel_, Nov 02 2019

%t Select[7*Range[500], Count[IntegerDigits[#], _?EvenQ]==0&] (* _Harvey P. Dale_, Jun 13 2011 *)

%o (PARI) is(n)=n%7==0 && #setintersect(Set(digits(n)), [0,2,4,6,8])==0 \\ _Charles R Greathouse IV_, Feb 15 2017

%Y Subsequence of A008589.

%Y Cf. A061826.

%K nonn,base,easy

%O 1,1

%A _Amarnath Murthy_, May 28 2001

%E More terms from Larry Reeves (larryr(AT)acm.org), May 30 2001