A057531 - OEIS

%I #32 Oct 27 2023 22:00:46

%S 1,2,11,22,36,84,101,152,156,170,202,208,225,228,288,301,372,396,441,

%T 444,468,516,525,530,602,684,710,732,804,828,882,952,972,1003,1016,

%U 1034,1070,1072,1106,1111,1164,1236,1304,1308,1425,1472,1476,1521,1524

%N Numbers whose sum of digits and number of divisors are equal.

%C [A007953(n)/A000005(n) = c] AND [A000005(n)/A007953(n) = c], c an integer. - _Ctibor O. Zizka_, Jun 26 2009

%H Giovanni Resta, <a href="/A057531/b057531.txt">Table of n, a(n) for n = 1..10000</a> (first 210 terms from Daniel Arribas)

%H Code Golf StackExchange, <a href="https://codegolf.stackexchange.com/questions/254910/find-the-nth-number-where-the-digit-sum-equals-the-number-of-factors">Find the nth number where the digit sum equals the number of factors</a>, coding challenge started Nov 28 2022.

%e 36 is a term as the sum of the digits of 36 is 3+6 = 9 and the number of divisors is 9 too.

%t Select[ Range[ 1000 ], DivisorSigma[ 0, # ]==Plus@@IntegerDigits[ # ]& ] (* _Harvey P. Dale_, Feb 19 2004 *)

%o See the Code Golf link.

%Y Cf. A000005, A007953, A057532, A050689, A070274, A070275, A063737, A067077.

%K nonn,easy,base

%O 1,2

%A _Asher Auel_, Sep 03 2000