

A104023


Numbers that have more than one way of being written as k^2*j with 0 < j <= k and gcd(k, j) = 1.


4



100, 196, 324, 484, 676, 900, 1089, 1156, 1444, 1521, 1764, 2028, 2116, 2304, 2500, 2601, 2916, 3249, 3364, 3468, 3600, 3844, 4332, 4356, 4624, 4761, 4900, 5476, 5625, 5776, 6084, 6348, 6498, 6724, 7056, 7396, 7500, 7569, 8100, 8464, 8649, 8820, 8836
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..43.


MATHEMATICA

t = Sort[ Flatten[ Table[ If[ GCD[k, j] == 1, k^2*j, {}], {k, 1000}, {j, k}]]]; u = Table[ Count[t, n], {n, 9215}]; Select[ Range[9215], u[[ # ]] > 1 &]


CROSSREFS

Cf. A104022, A102448, A104021.
Sequence in context: A025408 A068805 A231088 * A072367 A172178 A036742
Adjacent sequences: A104020 A104021 A104022 * A104024 A104025 A104026


KEYWORD

nonn


AUTHOR

Leroy Quet and Robert G. Wilson v, Feb 24 2005


STATUS

approved



