OFFSET
1,1
COMMENTS
The corresponding record values are 0, 1, 2, 3, 4, 6, 8, 9, 10, 11, 14, 15, ...
The bi-unitary version of A238895.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..73 (terms below 30000)
EXAMPLE
a(1) = 2 since it is the first number which is not the sum of proper bi-unitary divisors of any number.
a(2) = 6 since it is the least number which is the sum of proper bi-unitary divisors of one number: 6 = A331970(6).
MATHEMATICA
fun[p_, e_] := If[OddQ[e], (p^(e+1)-1)/(p-1), (p^(e+1)-1)/(p-1)-p^(e/2)]; bsigma[1] = 1; bsigma[n_] := Times @@ (fun @@@ FactorInteger[n]); bs[n_] := bsigma[n] - n; m = 300; v = Table[0, {m}]; Do[b = bs[k]; If[2 <= b <= m, v[[b]]++], {k, 1, m^2}]; s = {}; vm = -1; Do[If[v[[k]] > vm, vm = v[[k]]; AppendTo[s, k]], {k, 2, m}]; s
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Feb 03 2020
STATUS
approved