A068117 Smallest square beginning with concatenation of first n natural numbers.

1, 121, 12321, 1234321, 123454321, 12345654321, 1234567654321, 123456787654321, 12345678987654321, 1234567891022847726601, 12345678910116040727447056, 12345678910111210088193915136, 1234567891011121368630088707263161, 12345678910111213145200045239801398529

Offset

1,2

Links

Table of n, a(n) for n=1..14.

Example

a(3) = 12321 = 111^2.
a(10) = 1234567891022847726601 = 35136418301^2. [Corrected by Sean A. Irvine, Jan 28 2024]

Crossrefs

Cf. A007908.

Sequence in context: A002477 A173426 A261570 * A080162 A030174 A180153

Adjacent sequences: A068114 A068115 A068116 * A068118 A068119 A068120

Keyword

base,easy,nonn

Author

Amarnath Murthy, Feb 20 2002

Extensions

More terms from Ralf Stephan, Oct 12 2002

a(10) corrected and a(14) by Sean A. Irvine, Jan 28 2024

Status

approved