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

Author

Patrick De Geest, Nov 15 1998

Keywords

• nonn
• base

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