cp's OEIS Frontend

A171976 Numbers n such that the sum of the squares of the digits of n^n is a square.

%I A171976 #19 Sep 25 2018 20:29:29
%S A171976 0,1,2,8,10,100,123,209,312,1000,1668,2191,2268,4767,9338,10000,11004,
%T A171976 12248,12322,15926,17951,18202,19764,21807,29509,42647,43072,44750,
%U A171976 54237,56634,70383,74032,85325,90906,95261,100000
%N A171976 Numbers n such that the sum of the squares of the digits of n^n is a square.
%F A171976 {n: A003132(n^n) in A000290}.
%F A171976 {n: n^n in A175396.}
%e A171976 8 is in the sequence because 8^8 = 16777216 and 1^2+6^2+7^2+7^2+7^2+2^2+1^2+6^2
%e A171976   = 225 = 15^2.
%p A171976 with(numtheory): digits:=200:nn:=5000:for n from 0 to nn do:l:=length(n^n):n0:=n^n:s:=0:for
%p A171976   m from 1 to l do:q:=n0:u:=irem(q,10):v:=iquo(q,10):n0:=v :s:=s+u^2:od:if sqrt(s)=
%p A171976   floor(sqrt(s))then printf(`%d, `, n):else fi:od:
%t A171976 Join[{0},Select[Range[100000],IntegerQ[Sqrt[Total[IntegerDigits[ #^#]^2]]]&]] (* _Harvey P. Dale_, Sep 25 2018 *)
%o A171976 (PARI) isok(n) = my(d = digits(n^n)); issquare (sum(i=1, #d, d[i]^2)); \\ _Michel Marcus_, Jan 15 2014
%K A171976 nonn,base
%O A171976 1,3
%A A171976 _Michel Lagneau_, Nov 19 2010
%E A171976 Edited by _D. S. McNeil_, Nov 19 2010
%E A171976 Offset corrected and more terms added, _Michel Marcus_, Jan 15 2014