A038687 Concatenate i >= 1 and j >= 1, then sort.

11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 88, 89, 91, 92, 93, 94, 95, 96, 97, 98, 99, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy

Comments

Numbers with at least two nonzero decimal digits. - Charles R Greathouse IV, Jan 13 2015

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Programs

Maple

isA038687 := proc(n)
    local nzdigs,d ;
    nzdigs := 0 ;
    for d in convert(n,base,10) do
        if d > 0 then
            nzdigs := nzdigs+1 ;
        end if ;
    end do:
    simplify(nzdigs>=2 ) ;
end proc:
for n from 1 to 120 do
    if isA038687(n) then
        printf("%d,",n) ;
    end if;
end do: # R. J. Mathar, May 25 2023

Mathematica

Select[Range[150],Total[Most[DigitCount[#]]]>1&] (* Harvey P. Dale, Dec 15 2023 *)

PARI

is(n)=n/=10^valuation(n,10); n>9 \\ Charles R Greathouse IV, Jan 13 2015

Formula

a(n) = n + O(log n). - Charles R Greathouse IV, Jan 13 2015