A164773 - OEIS

%I #9 Apr 11 2023 21:02:46

%S 1667,2167,2383,2387,2437,2563,2567,2617,2626,2824,2828,2963,3143,

%T 3157,17313,19437,19917,21417,21633,22083,22113,22293,23214,23622,

%U 23664,23874,23937,24207,24228,24267,24417,24474,25824,25836,25863,26067

%N Numbers n with property that average digit of n^2 is s=7.

%H Harvey P. Dale, <a href="/A164773/b164773.txt">Table of n, a(n) for n = 1..925</a>

%e 1667^2=2778889 and (2+7+7+8+8+8+9)/7=7

%e 17313^2=299739969 and (2+9+9+7+3+9+9+6+9)/9=7.

%t Select[Range[30000],Mean[IntegerDigits[#^2]]==7&] (* _Harvey P. Dale_, Feb 22 2013 *)

%o (PARI) dsum(n)={my(s=0);while(n>9,s+=n%10;n\=10);s+n};

%o for(n=1,1e6,if(dsum(n^2)/#Str(n^2)==7,print1(n","))) \\ _Charles R Greathouse IV_, Nov 01 2009

%Y Subsequence of A164817.

%Y Average of digits of n^2 = s: A164771 (s=1), A164770 (s=2), A164782 (s=3), A164776 (s=4), A164774 (s=5), A164778 (s=6), A164773 (s=7), A164772 (s=8).

%K nonn,base

%O 1,1

%A _Zak Seidov_, Aug 26 2009