A034990 a(n)^2 is smallest square starting with a string of n 7's.
27, 88, 882, 8819, 278886, 881917, 8819171, 8819171, 2788866754, 2788866755, 27888667551, 881917103688, 8819171036882, 278886675511358, 2788866755113584, 27888667551135851, 88191710368819686, 278886675511358516, 8819171036881968635, 8819171036881968635
Offset: 1
Examples
a(5) = 278886^2 = {77777}400996.
References
- David Wells, 'Curious and Interesting Numbers', Penguin Books 1988, p. 184.
Crossrefs
Cf. A034991.
Extensions
More terms from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 23 2001
a(18) corrected and a(19), a(20) added by John Tomko, Nov 14 2006