A098121 - OEIS

%I #8 Jan 27 2021 05:35:06

%S 1,4,8,9,27,36,81,100,144,216,225,243,324,400,441,512,576,900,1000,

%T 1296,1521,1728,1764,2025,2304,2401,2601,2704,2916,3600,3969,4225,

%U 4356,4624,4913,5184,5832,6084,6400,7056,7744,7776,8000,8100,9216,10000,10404

%N Harshad numbers that are also perfect powers.

%H Amiram Eldar, <a href="/A098121/b098121.txt">Table of n, a(n) for n = 1..10000</a>

%e 1296 is a term because 6^4 = 1296 and 1+2+9+6 = 18 and 1296/18 = 72.

%t Select[Range[10^4], Divisible[#, Plus @@ IntegerDigits[#]] && (# == 1 || GCD @@ FactorInteger[#][[;; , 2]] > 1) &] (* _Amiram Eldar_, Jan 27 2021 *)

%Y Intersection of A001597 and A005349.

%K base,easy,nonn

%O 1,2

%A _Jason Earls_, Sep 24 2004