cp's OEIS Frontend

A061825 Multiples of 7 containing only odd digits.

%I A061825 #19 Nov 03 2019 01:44:10
%S A061825 7,35,77,91,119,133,175,315,357,371,399,511,539,553,595,735,777,791,
%T A061825 917,931,959,973,1113,1155,1197,1337,1351,1379,1393,1519,1533,1575,
%U A061825 1715,1757,1771,1799,1911,1939,1953,1995,3115,3157,3171,3199,3311,3339
%N A061825 Multiples of 7 containing only odd digits.
%H A061825 Robert Israel, <a href="/A061825/b061825.txt">Table of n, a(n) for n = 1..10000</a>
%H A061825 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%e A061825 315 = 7*45 is a term as it contains only odd digits.
%p A061825 R:= NULL:
%p A061825 for d from 1 to 4 do
%p A061825   for n from 5^d to 2*5^d-1 do
%p A061825     L:= map(t -> 2*t+1,convert(n,base,5)[1..d]);
%p A061825     x:= add(L[i]*10^(i-1),i=1..nops(L));
%p A061825     if x mod 7 = 0 then
%p A061825       R:= R, x;
%p A061825     fi;
%p A061825 od od:
%p A061825 R; # _Robert Israel_, Nov 02 2019
%t A061825 Select[7*Range[500], Count[IntegerDigits[#], _?EvenQ]==0&] (* _Harvey P. Dale_, Jun 13 2011 *)
%o A061825 (PARI) is(n)=n%7==0 && #setintersect(Set(digits(n)), [0,2,4,6,8])==0 \\ _Charles R Greathouse IV_, Feb 15 2017
%Y A061825 Subsequence of A008589.
%Y A061825 Cf. A061826.
%K A061825 nonn,base,easy
%O A061825 1,1
%A A061825 _Amarnath Murthy_, May 28 2001
%E A061825 More terms from Larry Reeves (larryr(AT)acm.org), May 30 2001