OFFSET
1,2
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000
EXAMPLE
From David A. Corneth, Aug 20 2020: (Start)
202 is in the sequence as the divisors of 202 are 1, 2, 101, 202 and none have two digits (in base 10).
20 isn't in the sequence as 20 is divisible by 10 which has two digits in base 10 and isn't 20. (End)
MATHEMATICA
ntdfQ[n_]:=Union[IntegerLength[#]==2&/@Most[Divisors[n]]]=={False}; Join[ {1}, Select[Range[250], ntdfQ]] (* Harvey P. Dale, Sep 26 2021 *)
PROG
(PARI) is(n) = for(i = 10, min(n-1, 99), if(n % i == 0, return(0))); 1 \\ David A. Corneth, Aug 20 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Henry Bottomley, Mar 14 2000
STATUS
approved