A087143 Numbers n such that sum of digits of n is divisible by digital root of n.
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 45, 46, 48, 50, 51, 52, 53, 54, 55, 57, 60, 61, 62, 63, 64, 66, 70, 71, 72, 73, 75, 80, 81, 82, 84, 90
Offset: 1
Examples
84 is a term because 12 (its sum of digits) is divisible by 3 (its digital root).
Links
- Nathaniel Johnston, Table of n, a(n) for n = 1..10000
Programs
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Maple
A087143 := proc(n) option remember: local k: if(n=1)then return 1:fi: for k from procname(n-1)+1 do if(add(d, d=convert(k,base,10)) mod (((k-1) mod 9) + 1) = 0)then return k: fi: od: end: seq(A087143(n),n=1..100); # Nathaniel Johnston, May 05 2011
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Mathematica
sddrQ[n_]:=Module[{sd=Total[IntegerDigits[n]],dr},dr=sd;While[dr>9, dr= Total[ IntegerDigits[dr]]];Divisible[sd,dr]]; Select[Range[100],sddrQ] (* Harvey P. Dale, May 22 2013 *) -
PARI
is(n)=sumdigits(n)%((n-1)%9+1) == 0 \\ Charles R Greathouse IV, Oct 13 2022
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