OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
10 is a term since all of its divisors exclusing 1, i.e., 2, 5 and 10, or 110, 101, and 11110 in negabinary representation, have an even number of 1's.
MATHEMATICA
negaBinWt[n_] := negaBinWt[n] = If[n==0, 0, negaBinWt[Quotient[n-1, -2]] + Mod[n, 2]]; eveNegaBinQ[n_] := EvenQ[negaBinWt[n]]; seqQ[n_] := AllTrue[Rest @ Divisors[n], eveNegaBinQ]; Select[Range[401], seqQ]
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amiram Eldar, Jan 28 2020
STATUS
approved