The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A303482 Numbers k such that the average of all distinct prime factors of all positive integers <= k is an integer. 2
 2, 5, 81, 10742, 10130527, 1041972864, 23292549600 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers k such that A013939(k)|A024924(k). LINKS Eric Weisstein's World of Mathematics, Distinct Prime Factors EXAMPLE 5 is in the sequence because the distinct prime factors of 2, 3, 4, and 5 are 2, 3, 2 and 5 respectively and their average (2 + 3 + 2 + 5) / 4 = 3 is an integer. - David A. Corneth, Apr 26 2018 MATHEMATICA s = t = 0; k = 2; lst = {}; While[k < 1000000000, p = #[[1]] & /@ FactorInteger@ k; s = s + Plus @@ p; t = t + Length@ p; If[ Mod[s, t] == 0, AppendTo[lst, k]]; k++]; lst (* Robert G. Wilson v, Apr 26 2018 *) CROSSREFS Cf. A001221, A008472, A013939, A024924, A078174, A078175, A226647, A284755, A303480. Sequence in context: A127997 A096266 A123978 * A290952 A201113 A309089 Adjacent sequences:  A303479 A303480 A303481 * A303483 A303484 A303485 KEYWORD nonn,more AUTHOR Ilya Gutkovskiy, Apr 24 2018 EXTENSIONS a(5) from Daniel Suteu, Apr 24 2018 a(6)-a(7) from Giovanni Resta, Apr 26 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 5 13:26 EDT 2020. Contains 333241 sequences. (Running on oeis4.)