A113243 Differences of nonzero tetranacci numbers.

0, 1, 2, 3, 4, 6, 7, 11, 13, 14, 21, 25, 27, 28, 41, 48, 52, 54, 55, 79, 93, 100, 104, 106, 107, 152, 179, 193, 200, 204, 206, 207, 293, 345, 372, 386, 393, 397, 399, 400, 565, 665, 717, 744, 758, 765, 769, 771, 772, 1089, 1282, 1382, 1434, 1461, 1475, 1482

Offset: 1

Author

Jonathan Vos Post, Oct 19 2005; corrected Oct 20 2005

Keywords

• easy
• nonn

Links

• R. J. Mathar, Table of n, a(n) for n = 1..197

Crossrefs

Cf. A000078, A113244.

Programs

Maple

isA113243 := proc(n)
    local i,j ;
    for j from 3 do
        for i from 3 to j do
            if A000078(j) - A000078(i) = n then
                return true;
            elif A000078(j) - A000078(i) < n then
                break ;
            end if;
        end do:
        if A000078(j) - A000078(j-1) > n then
            return false;
        end if;
    end do:
end proc:
for n from 0 to 10000 do
    if isA113243(n) then
        printf("%d,",n) ;
    end if;
end do: # R. J. Mathar, Oct 04 2014

Mathematica

Union[Flatten[Differences/@Subsets[Drop[LinearRecurrence[{1, 1, 1,1}, {0,0, 0, 1}, 16],3],{2}]]] (* James C. McMahon, Jun 23 2024 *)

Formula

{a(n)} = { A000078(i) - A000078(j) such that i>=j>=3 }.