A035033 Numbers k such that k <= d(k)^2, where d() = number of divisors (A000005).
1, 2, 3, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24, 28, 30, 32, 36, 40, 42, 48, 54, 56, 60, 72, 80, 84, 90, 96, 108, 120, 126, 132, 140, 144, 168, 180, 192, 210, 216, 240, 252, 288, 300, 336, 360, 420, 480, 504, 540, 720, 840, 1260
Offset: 1
Programs
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Mathematica
Select[Range[1300],#<=DivisorSigma[0,#]^2&] (* Harvey P. Dale, Mar 16 2012 *)
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PARI
is(n)=numdiv(n)^2>=n \\ Charles R Greathouse IV, Aug 03 2012