A181319 Numbers n with property that there is a different number m such that the lunar squares n*n and m*m are the same.

11011, 11012, 11013, 11014, 11015, 11016, 11017, 11018, 11019, 11021, 11022, 11023, 11024, 11025, 11026, 11027, 11028, 11029, 11031, 11032, 11033, 11034, 11035, 11036, 11037, 11038, 11039, 11041, 11042, 11043, 11044, 11045, 11046, 11047, 11048, 11049, 11051, 11052, 11053, 11054, 11055, 11056, 11057, 11058

Offset

1,1

Links

David Applegate and N. J. A. Sloane, Table of n, a(n) for n = 1..21894

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]

Example

11011*11011 = 11111*11111 = 111111111, so 11011 and 11111 are members.

Prog

(ksh script from David Applegate; assumes the dismal C program dismal2a has been installed)
i=0
while [ $i -lt 100000 ]; do
  echo $i $(dismal2a -d mul $i $i)
  i=$(($i+1))
done | awk '{
  nrt[$2]++;
  rt[$2]=rt[$2] " " $1;
}
END{
  for (i in rt)
    if (nrt[i] > 1)
      print i, rt[i];
}' | sort -k1, 1n > dismal_multsquares.txt

Crossrefs

Cf. A087019, A180513.

Sequence in context: A267038 A267293 A300557 * A267811 A267934 A218598

Adjacent sequences: A181316 A181317 A181318 * A181320 A181321 A181322

Keyword

nonn,base

Author

David Applegate and N. J. A. Sloane, Jan 26 2011

Status

approved