cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A061811 Multiples of 3 with all even digits.

Original entry on oeis.org

0, 6, 24, 42, 48, 60, 66, 84, 204, 222, 228, 240, 246, 264, 282, 288, 402, 408, 420, 426, 444, 462, 468, 480, 486, 600, 606, 624, 642, 648, 660, 666, 684, 804, 822, 828, 840, 846, 864, 882, 888, 2004, 2022, 2028, 2040, 2046, 2064, 2082, 2088, 2202, 2208
Offset: 1

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Author

Amarnath Murthy, May 28 2001

Keywords

Comments

The numbers b(d) of terms from 10^(d-1) to 10^d satisfy the recurrence b(d) = 6 b(d-1) - 6 b(d-2) + 5 b(d-3) with b(1)=1, b(2)=6, b(3)=33. For d >= 4, b(d) = (3*A276508(d) - 10*A276508(d-1) + 3*A276508(d-2))/7. - Robert Israel, Feb 15 2017

Examples

			228 has all even digits and 228 = 3*76.
		

Crossrefs

Programs

  • Maple
    N:= 4: # for all terms < 10^N
    E[1,0]:= {6}:
    E[1,1]:= {4}:
    E[1,2]:= {2,8}:
    for n from 2 to N do
      for j from 0 to 2 do
        E[n,j]:= map(t -> (10*t, 10*t+6),E[n-1,j]) union
                 map(t -> (10*t+2, 10*t+8), E[n-1,j+1 mod 3]) union
               map(t -> 10*t+4, E[n-1,j+2 mod 3]);
    od od:
    A:=sort([0,seq(op(E[i,0]),i=1..N)]); # Robert Israel, Feb 15 2017
  • Mathematica
    Select[3*Range[0,800],AllTrue[IntegerDigits[#],EvenQ]&] (* Harvey P. Dale, May 03 2025 *)
  • PARI
    is(n)=n%3==0 && #setintersect(Set(digits(n)), [1,3,5,7,9])==0 \\ Charles R Greathouse IV, Feb 15 2017

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 30 2001
Offset corrected by Charles R Greathouse IV, Feb 15 2017