A368049 Perfect squares whose decimal expansion consists of k > 1 digits, k-1 of which are equal.

16, 25, 36, 49, 64, 81, 100, 121, 144, 225, 400, 441, 484, 676, 900, 1444, 10000, 40000, 44944, 90000, 1000000, 4000000, 9000000, 100000000, 400000000, 900000000, 10000000000, 40000000000, 90000000000, 1000000000000, 4000000000000, 9000000000000, 100000000000000

Offset

1,1

Comments

The terms > 90000 are of one of the following three forms: 10^(2*j), 4*10^(2*j) or 9*10^(2*j) where j is an integer >= 3.

See Gica/Panaitopol link for proof of above comment. - Ray Chandler, Jan 16 2024

Links

Ray Chandler, Table of n, a(n) for n = 1..1000

Alexandru Gica and Laurențiu Panaitopol, On Oblath's Problem, J. Integer Seq., Vol. 6 (2003), article 03.3.5, 12 pp.

Index entries for linear recurrences with constant coefficients, signature (0,0,100).

Formula

a(n) = 100*a(n-3) for n > 22. - Stefano Spezia, Dec 09 2023

Crossrefs

Cf. A235717, A018885.

Subsequence of A000290.

Sequence in context: A374934 A245371 A235717 * A319388 A291334 A175689

Adjacent sequences: A368046 A368047 A368048 * A368050 A368051 A368052

Keyword

nonn,base,easy

Author

José Hernández, Dec 09 2023

Status

approved