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Numbers with digital root equal to their number of divisors.
1

%I #7 Dec 15 2017 17:36:06

%S 1,2,11,22,29,36,47,58,83,85,94,101,137,152,166,170,173,191,202,225,

%T 227,247,263,265,274,281,296,301,317,319,346,353,355,382,389,391,427,

%U 441,443,445,454,461,479,481,494,517,526,530,535,553,562,569,584,587

%N Numbers with digital root equal to their number of divisors.

%H Harvey P. Dale, <a href="/A076206/b076206.txt">Table of n, a(n) for n = 1..10000</a>

%e a(6)=36 because 3+6=9 and 36 has 9 divisors.

%t drndQ[n_]:=NestWhile[Total[IntegerDigits[#]]&,n,#>9&]==DivisorSigma[0,n]; Select[Range[600],drndQ] (* _Harvey P. Dale_, Apr 03 2013 *)

%Y Cf. A000005, A010888.

%K base,easy,nonn

%O 1,2

%A _Jason Earls_, Nov 02 2002