A034990 - OEIS

%I #11 Oct 09 2019 03:03:28

%S 27,88,882,8819,278886,881917,8819171,8819171,2788866754,2788866755,

%T 27888667551,881917103688,8819171036882,278886675511358,

%U 2788866755113584,27888667551135851,88191710368819686,278886675511358516,8819171036881968635,8819171036881968635

%N a(n)^2 is smallest square starting with a string of n 7's.

%D David Wells, 'Curious and Interesting Numbers', Penguin Books 1988, p. 184.

%e a(5) = 278886^2 = {77777}400996.

%Y Cf. A034991.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Nov 15 1998

%E More terms from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 23 2001

%E a(18) corrected and a(19), a(20) added by John Tomko, Nov 14 2006