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A202082 In base-2 lunar arithmetic, a(n) is the smallest number that has exactly n different square roots (or -1 if no such number exists). 1
1, 111111111, 11111111111, 1011111111111111101, 1111111111111, 10111111111111111, 11100111111111111111111, 101111111111111111101, 111111111111111, 1011111111111111111, 1010111111111111111111101, 1110011111111111111111111, 10111111111111111111101, 11101111111111111111111, 11111111111111111, 1111111111111111111010000, 1111111111111111111111001 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The numbers are written in base 2.

LINKS

Table of n, a(n) for n=1..17.

D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing], Journal of Integer Sequences, Vol. 14 (2011), #11.9.8.

Index entries for sequences related to dismal (or lunar) arithmetic

EXAMPLE

111111111 has two square roots, 11011 and 11111;

11111111111 has 3 square roots, 110111, 111011, 11111.

CROSSREFS

Cf. A191701, A202174.

Sequence in context: A202174 A172525 A038451 * A262499 A068538 A186552

Adjacent sequences:  A202079 A202080 A202081 * A202083 A202084 A202085

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Dec 13 2011

STATUS

approved

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Last modified June 26 16:18 EDT 2022. Contains 354885 sequences. (Running on oeis4.)