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

1,1

Links

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

Example

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.

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 *)

Crossrefs

Cf. A001065, A023883, A032741, A048747.

Sequence in context: A229063 A025212 A024972 * A355527 A336905 A097889

Adjacent sequences: A048746 A048747 A048748 * A048750 A048751 A048752

Keyword

easy,nonn

Author

Enoch Haga

Status

approved