A034087 - OEIS

%I #28 Jan 10 2025 09:04:53

%S 1,10,20,50,100,110,111,120,130,133,200,210,240,267,298,310,315,360,

%T 372,376,400,420,480,500,532,550,630,803,917,973,1000,1010,1011,1020,

%U 1030,1071,1100,1101,1110,1134,1148,1200,1211,1222,1290,1300,1302,1316

%N Numbers divisible by the sum of the squares of their digits.

%H Amiram Eldar, <a href="/A034087/b034087.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..3465 from Carmine Suriano)

%F A003132[a(n)] | a(n). - _R. J. Mathar_, Feb 25 2007

%e a(100) = 4131 since 4^2+1^2+3^2+1^2=27 divides 4131. - _Carmine Suriano_, May 04 2013

%p isA034087 := proc(n) if n mod A003132(n) = 0 then true ; else false ; end if ; end proc:

%p for n from 1 to 1800 do if isA034087(n) then printf("%d ",n) ; end if ; end do ; # _R. J. Mathar_, Feb 25 2007

%t Select[Range[1500], Divisible[#, Plus @@ (IntegerDigits[#]^2)] &] (* _Amiram Eldar_, Jan 31 2021 *)

%o (PARI) isok(m) = !(m % norml2(digits(m))); \\ _Michel Marcus_, Jan 31 2021

%o (Python)

%o def ok(n): return n and n%sum(di**2 for di in map(int, str(n))) == 0

%o print([k for k in range(1317) if ok(k)]) # _Michael S. Branicky_, Jan 10 2025

%Y Cf. A003132, A034088, A169665, A169666.

%K base,easy,nonn

%O 1,2

%A _Erich Friedman_