cp's OEIS Frontend

A028373 Numbers that have only the straight digits {1, 4, 7}.

%I A028373 #17 Jul 25 2015 12:53:29
%S A028373 1,4,7,11,14,17,41,44,47,71,74,77,111,114,117,141,144,147,171,174,177,
%T A028373 411,414,417,441,444,447,471,474,477,711,714,717,741,744,747,771,774,
%U A028373 777,1111,1114,1117,1141,1144,1147,1171,1174,1177,1411,1414,1417,1441
%N A028373 Numbers that have only the straight digits {1, 4, 7}.
%H A028373 Alois P. Heinz, <a href="/A028373/b028373.txt">Table of n, a(n) for n = 1..1000</a>
%p A028373 a:= proc(n) local d, i, m, r; m:=n; r:=0;
%p A028373       for i from 0 while m>0 do
%p A028373         d:= irem(m, 3, 'm');
%p A028373         if d=0 then d:=3; m:=m-1 fi;
%p A028373         r:= r+10^i*[1, 4, 7][d]
%p A028373       od: r
%p A028373     end:
%p A028373 seq(a(n), n=1..100);  # _Alois P. Heinz_, May 25 2014
%t A028373 f[n_] := Block[{id = IntegerDigits[n], straight = {1, 4, 7}}, If[ Union[ Join[id, straight]] == straight, True, False]]; Select[ Range[0, 1446], f[ # ] & ]
%t A028373 FromDigits/@Flatten[Table[Tuples[{1,4,7},n],{n,4}],1] (* _Harvey P. Dale_, Jul 25 2015 *)
%o A028373 (PARI) is(n)=my(t);while(n,t=n%10;if(t!=1&&t!=4&&t!=7,return(0));n\=10);!!t \\ _Charles R Greathouse IV_, Sep 25 2012
%Y A028373 Cf. A028374, the curved sequence.
%Y A028373 Cf. A079651 prime numbers using only the straight digits 1,4,7.
%K A028373 easy,nonn,base
%O A028373 1,2
%A A028373 Greg Heil (gheil(AT)scn.org), Dec 11 1999