A023196 - OEIS (original) (raw)

6, 12, 18, 20, 24, 28, 30, 36, 40, 42, 48, 54, 56, 60, 66, 70, 72, 78, 80, 84, 88, 90, 96, 100, 102, 104, 108, 112, 114, 120, 126, 132, 138, 140, 144, 150, 156, 160, 162, 168, 174, 176, 180, 186, 192, 196, 198, 200, 204, 208, 210, 216, 220, 222, 224, 228, 234, 240, 246, 252

COMMENTS

Also called the non-deficient numbers.

If k is a term, so is every positive multiple of k. The "primitive" terms form A006039.

The sequence of numbers k that give local minima for A004125, i.e., such that A004125(k-1) > A004125(k) and A004125(k) < A004125(k+1) coincides with this sequence for the first 1014 terms. Then there appears 4095 which is a term of A023196 but is not a local minimum. - Max Alekseyev, Jan 26 2005

Like the abundant numbers, this sequence has density between 0.2474 and 0.2480, see A005101. - Charles R Greathouse IV, Nov 30 2022

MATHEMATICA

Select[Range[300], DivisorSigma[1, #] >= 2# &] (* Harvey P. Dale, Sep 26 2014 *)

PROG

(GAP) Filtered([1..260], n->Sigma(n)>=2*n); # Muniru A Asiru, Dec 04 2018

(Magma) [n: n in [1..300] | not (2*n gt DivisorSigma(1, n))]; // Vincenzo Librandi, Dec 05 2018