A number n is a self number if there is no number g such that g + the sum of g's digits = n. So 18 is not a self number because 9+9=18, 43 is not a self number because 35+5+3=43.


The task is:

 Display the first 50 self numbers;
 I believe that the 100000000th self number is 1022727208. You should either confirm or dispute my conjecture.

224036583-1 is a Mersenne prime, claimed to also be a self number. Extra credit to anyone proving it.


See also
 
OEIS: A003052 - Self numbers or Colombian numbers
Wikipedia: Self numbers
 
// Self numbers. Nigel Galloway: October 6th., 2020
let fN g=let rec fG n g=match n/10 with 0->n+g |i->fG i (g+(n%10)) in fG g g
let Self=let rec Self n i g=seq{let g=g@([n..i]|>List.map fN) in yield! List.except g [n..i]; yield! Self (n+100) (i+100) (List.filter(fun n->n>i) g)} in Self 0 99 []  
 
Self |> Seq.take 50 |> Seq.iter(printf "%d "); printfn ""
printfn "\n%d" (Seq.item 99999999 Self)
 