OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..48 (terms < 10^12)
EXAMPLE
60 is a term since there is only one partition of its set of unitary divisors, {1, 3, 4, 5, 12, 15, 20, 60}, into 2 disjoint sets whose sum is equal: 1 + 3 + 4 + 5 + 12 + 15 + 20 = 60.
MATHEMATICA
uzQ[n_] := Module[{d = Select[Divisors[n], CoprimeQ[#, n/#] &], sum, x}, sum = Plus @@ d; If[sum < 2*n || OddQ[sum], False, CoefficientList[Product[1 + x^i, {i, d}], x][[1 + sum/2]] == 2]]; Select[Range[6000], uzQ]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, May 26 2020
EXTENSIONS
Terms a(19) and beyond from Giovanni Resta, May 30 2020
STATUS
approved