|
%I #13 Oct 10 2019 23:35:41
%S 2,12,38,212,2538,6888,66592,210771,2059962,6696592,21081538,
%T 209868112,664488107,3800598038,18613286762,209820981888,666669703412,
%U 666516649788,6666894662768,49400874945738
%N a(n)^2 is the smallest square containing exactly n 4's.
%C a(21) > 10^14. - _Giovanni Resta_, Jul 27 2018
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SquareNumber.html">Square Number</a>
%t a[n_] := Block[{k=1}, While[DigitCount[k^2, 10, 4] != n, k++]; k]; Array[a, 7] (* _Giovanni Resta_, Jul 27 2018 *)
%Y Cf. A036511, A034984.
%K nonn,base,more
%O 1,1
%A _Patrick De Geest_, Mar 15 1999
%E More terms from _Jon E. Schoenfield_, Jan 14 2009
%E a(17)-a(20) from _Giovanni Resta_, Jul 27 2018
|
