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A234814 Numbers that are divisible by their digital sum but not by their digital root. 1
195, 209, 247, 266, 285, 375, 392, 407, 465, 476, 481, 518, 555, 592, 605, 629, 644, 645, 715, 735, 736, 782, 803, 825, 880, 915, 935, 1066, 1095, 1148, 1168, 1183, 1185, 1274, 1275, 1365, 1394, 1417, 1455, 1526, 1534, 1545, 1547, 1635, 1651, 1652, 1679, 1725, 1744, 1815, 1853, 1886, 1898, 1904, 1905 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These are the Harshad numbers which are missing from A234474.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics,Harshad number

EXAMPLE

195 is a term as it is divisible by its digital sum i.e. 15 but not by its digital root i.e. 6.

MATHEMATICA

Select[Range@1905, Mod[#, 1 + Mod[#-1, 9]] > 0 && Mod[#, Plus@@ IntegerDigits@ #] == 0 &] (* Giovanni Resta, Jan 03 2014 *)

PROG

(C++)

#include<iostream.h>

int digitalsum(int n){int sum=0; while(n>0){sum+=n%10; n/=10; }return(sum); }

int digitalroot(int a){return(1+(a-1)%9); }

int main(){for(int i=1; i<=2000; i++){

if(i%(digitalroot(i))!=0 &&  i%(digitalsum(i))==0) cout<<i<<", "; }}

(Haskell)

a234814 n = a234814_list !! (n-1)

a234814_list = filter (\x -> x `mod` a007953 x == 0 &&

                             x `mod` a010888 x /= 0) [1..]

-- Reinhard Zumkeller, Mar 04 2014

CROSSREFS

Cf. A005349, A234474.

Cf. A064807, A007953, A010888.

Sequence in context: A296893 A045073 A204811 * A154938 A234100 A080394

Adjacent sequences:  A234811 A234812 A234813 * A234815 A234816 A234817

KEYWORD

nonn,base

AUTHOR

Mihir Mathur, Dec 31 2013

STATUS

approved

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Last modified December 12 12:50 EST 2019. Contains 329958 sequences. (Running on oeis4.)