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

Author

Erich Friedman, Labos Elemer

Keywords

• nonn
• fini
• full

Crossrefs

Cf. A000005, A035034, A035035, A033950, A036763, A034884, A273323.

Programs

Mathematica

Select[Range[1300],#<=DivisorSigma[0,#]^2&] (* Harvey P. Dale, Mar 16 2012 *)

PARI

is(n)=numdiv(n)^2>=n \\ Charles R Greathouse IV, Aug 03 2012