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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
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 28 19:10 EDT 2022. Contains 354907 sequences. (Running on oeis4.)