OFFSET
1,1
COMMENTS
2^33 < a(9) <= A005820(6) = 51001180160.
MATHEMATICA
Select[Range[6*10^5], #3 == #1 + 3 #2 & @@ Prepend[Map[If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]] &, {#, DivisorSigma[1, #]}], #] &] (* Michael De Vlieger, Feb 25 2022 *)
PROG
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Antti Karttunen, Apr 08 2021
EXTENSIONS
a(8) from Antti Karttunen, Feb 25 2022
STATUS
approved