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.

A171949 P-positions for game of Mark-4.

Original entry on oeis.org

0, 4, 8, 12, 20, 24, 28, 36, 40, 44, 52, 56, 60, 64, 68, 72, 76, 84, 88, 92, 100, 104, 108, 116, 120, 124, 128, 132, 136, 140, 148, 152, 156, 164, 168, 172, 180, 184, 188, 192, 196, 200, 204, 212, 216, 220, 228, 232, 236, 244, 248, 252, 260, 264, 268, 276
Offset: 1

Views

Author

N. J. A. Sloane, Oct 29 2010

Keywords

Crossrefs

Complement of A171948.
Cf. A217319.

Programs

  • Maple
    isA171948 := proc(n)
        option remember;
        if n <=3 then
            true;
        elif isA171949(n) then
            false;
        else
            true ;
        end if;
    end proc:
    isA171949 := proc(n)
        option remember;
        if n mod 4 <> 0 then
            return false;
        end if;
        if isA171948(n/4) then
            true;
        else
            false ;
        end if;
    end proc:
    for n from 0 to 400 do
        if isA171949(n) then
            printf("%d,",n);
        end if;
    end do: # R. J. Mathar, Mar 28 2013
  • Mathematica
    isA171948[n_] := isA171948[n] =
       If[n <= 3, True, If[isA171949[n], False, True]];
    isA171949[n_] := isA171949[n] =
       If[Mod[n, 4] != 0, False, If[isA171948[n/4], True, False]];
    Select[Range[0, 400], isA171949] (* Jean-François Alcover, Apr 16 2023, after R. J. Mathar *)

Formula

a(n) = 4*A171948(n).
Conjecture: For n>=2, a(n) = A217319(n-1). - Vladimir Shevelev, Mar 18 2013