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A211822
Nonprime numbers with all divisors with additive digital root of 1.
3
1, 361, 703, 1369, 1387, 2071, 2413, 2701, 3097, 3439, 3781, 4033, 4699, 5149, 5329, 5833, 6031, 6697, 6859, 7201, 7363, 7543, 7957, 8227, 9253, 9271, 9937, 10027, 10279, 10963, 11359, 11647, 11881, 11899, 11989, 13213, 13357
OFFSET
1,2
COMMENTS
Complement of A061237 (prime numbers == 1 (mod 9)) with respect to A211821.
LINKS
EXAMPLE
Number 6859 with divisors 1, 19, 361, 6859 is in sequence because all divisors have additive digital root of 1.
MAPLE
filter:= n -> not isprime(n) and numtheory:-factorset(n) mod 9 = {1}:
filter(1):= true:
select(filter, [seq(i, i=1..20000, 9)]); # Robert Israel, May 10 2020
MATHEMATICA
(* First run the program for A211821 *) Select[A211821, Not[PrimeQ[#]] &] (* Alonso del Arte, May 02 2012 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Apr 26 2012
STATUS
approved