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, 111111111, 11111111111, 1011111111111111101, 1111111111111, 10111111111111111, 11100111111111111111111, 101111111111111111101, 111111111111111, 1011111111111111111, 1010111111111111111111101, 1110011111111111111111111, 10111111111111111111101, 11101111111111111111111, 11111111111111111, 1111111111111111111010000, 1111111111111111111111001

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