A241079 If n is a perfect square, a(n) = 0. If n is not a perfect square, a(n) is the number of final digits necessary to rule out n as a perfect square, or -1 if cannot be ruled out as a perfect square using any group of final digits.

0, 1, 1, 0, 2, 2, 1, 1, 0, 2, 2, 1, 1, 2, 2, 0, 1, 1, 2, 2, 3, 1, 1, 4, 0, 2, 1, 1, 3, 2, 2, 1, 1, 2, 2, 0, 1, 1, 2, 2, -1, 1, 1, 4, 2, 2, 1, 1, 0, 2, 2, 1, 1, 2, 2, 4, 1, 1, 2, 2, 3, 1, 1, 0, 2, 2, 1, 1, 3, 2, 2, 1, 1, 2, 2, 4, 1, 1, 2, 2, 0, 1, 1, 5, 2, 2, 1

Offset

1,5

Comments

To define the n-digit ending of a number with fewer than n digits, insert 0's in front of it. For example, the 2-digit ending of 5 is 05.

Links

Table of n, a(n) for n=1..87.

Example

a(24) cannot be 3 because 024 is a valid ending of a square (32^2 = 1024).

Crossrefs

Cf. A241081 (numbers k such that a(k) = -1).

Sequence in context: A269317 A119557 A125919 * A061198 A195011 A290942

Adjacent sequences: A241076 A241077 A241078 * A241080 A241081 A241082

Keyword

sign,base

Author

J. Lowell, Apr 15 2014

Extensions

Terms corrected by and more terms from Jinyuan Wang, Aug 21 2021

Status

approved