

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.


4



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
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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: A251873 A267038 A267293 * 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



