A082741 Numbers that have digits consisting only of line segments or both line segments and curves (base 10 digits are 1, 2, 4, 5, 7).

1, 2, 4, 5, 7, 11, 12, 14, 15, 17, 21, 22, 24, 25, 27, 41, 42, 44, 45, 47, 51, 52, 54, 55, 57, 71, 72, 74, 75, 77, 111, 112, 114, 115, 117, 121, 122, 124, 125, 127, 141, 142, 144, 145, 147, 151, 152, 154, 155, 157, 171, 172, 174, 175, 177, 211, 212, 214, 215, 217, 221

Offset: 1

Author

Rick L. Shepherd, May 21 2003

Keywords

• base
• nonn
• easy

Comments

This sequence allows the digits 2 and 5, formed from combinations of line segments and curves; the subsequence A028373 does not.

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..1000
• Index entries for 10-automatic sequences.

Crossrefs

Cf. A028373 (line-segment digits 1, 4, 7 only), A028374 (digits with curves or both curves and line segments), A072960 (curved digits 0, 3, 6, 8, 9 only).

Programs

Maple

a:= proc(n) local d, i, m, r; m:=n; r:=0;
      for i from 0 while m>0 do
        d:= irem(m, 5, 'm');
        if d=0 then d:=5; m:=m-1 fi;
        r:= r+10^i*[1, 2, 4, 5, 7][d]
      od: r
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, May 25 2014

Mathematica

Table[FromDigits/@Tuples[{1,2,4,5,7},n],{n,3}]//Flatten (* Harvey P. Dale, Apr 17 2022 *)