A068178 a(1) = 4; for n>1, a(n) is the smallest square > a(n-1) obtained by inserting digits into a(n-1).

4, 49, 1849, 18496, 1784896, 177848896, 17778488896, 1777784888896, 177777848888896, 17777778488888896, 1777777784888888896, 177777777848888888896, 17777777778488888888896, 1777777777784888888888896, 177777777777848888888888896, 17777777777778488888888888896

Offset

1,1

Links

Table of n, a(n) for n=1..16.

Example

a(2)=49 hence a(3) = 1849 the smallest square formed from 49.

Crossrefs

Cf. A068175, A068176, A068177, A091877 gives square roots.

Sequence in context: A263441 A067717 A067714 * A050630 A080808 A284328

Adjacent sequences: A068175 A068176 A068177 * A068179 A068180 A068181

Keyword

base,nonn

Author

Amarnath Murthy, Feb 25 2002

Extensions

Corrected and extended by Ray Chandler, Oct 11 2003

a(14)-a(16) from Pontus von Brömssen, Feb 05 2026

Status

approved