A281528 a(n) = least numerator k such that the proper fraction k/n needs three or more terms as a signed sum of distinct unit fraction, or 0 if no such numerator exists.

0, 0, 0, 0, 0, 5, 0, 7, 0, 7, 0, 5, 10, 11, 11, 5, 13, 7, 13, 13, 14, 5, 17, 7, 10, 11, 17, 8, 19, 7, 13, 13, 10, 11, 23, 5, 11, 11, 17, 9, 25, 5, 17, 13, 10, 5, 29, 9, 14, 11, 19, 5, 22, 13, 17, 13, 11, 7, 37, 7, 13, 13, 19, 17, 26, 5, 20, 15, 22, 11, 29, 5, 10

Offset: 2

Author

Arkadiusz Wesolowski, Jan 23 2017

Keywords

• nonn

Links

• Index entries for sequences related to Egyptian fractions

Crossrefs

Cf. A281527.

Programs

Magma

lst:=[]; for n in [2..74] do for k in [1..n-1] do f:=k/n; x:=1; v:=0; if Numerator(f) eq 1 then v:=1; else while f lt 2/x do if Numerator(Abs(f-1/x)) eq 1 then v:=1; break; end if; x+:=1; end while; end if; if v eq 0 then Append(~lst, k); break; end if; if k eq n-1 then Append(~lst, 0); end if; end for; end for; lst;