A048749 Factor n, divide sum of aliquot divisors by number of aliquot divisors; append n to sequence if quotient is integral and not previously seen.

6, 15, 30, 33, 44, 49, 51, 69, 81, 87, 114, 117, 120, 123, 124, 141, 159, 164, 170, 177, 213, 244, 249, 252, 267, 270, 276, 282, 284, 303, 320, 321, 339, 345, 366, 393, 404, 411, 427, 447, 462, 501, 511, 513, 519, 524, 529, 534, 537, 570, 573, 590, 591, 604

Offset: 1

Author

Enoch Haga

Keywords

• easy
• nonn

Examples

			a(2)=15; for n=15 the sum of aliquot divisors is 9; number of aliquot divisors is 3; 9/3=3. The quotient 3 is the mean aliquot divisor and this is the first time that 3 has occurred.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001065, A023883, A032741, A048747.

Programs

Mathematica

(Select[{Mean[Most[Divisors[#]]], #}& /@ Select[Range[300], CompositeQ], IntegerQ[#[[1]]]&] // Sort // Split[#, #1[[1]] == #2[[1]]&]&)[[All, 1]][[All, 2]] // Sort (* Amiram Eldar, Sep 06 2019 after Jean-François Alcover at A048747 *)