The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A348032 Multiply-perfect numbers k that do not have a divisor d such that sigma(d)*d = k. 1
 2178540, 45532800, 459818240, 1476304896, 14182439040, 31998395520, 43861478400, 51001180160, 518666803200, 704575228896, 13661860101120, 30823866178560, 181742883469056, 740344994887680, 796928461056000, 6088728021160320, 20158185857531904, 212517062615531520, 622286506811515392, 69357059049509038080, 87934476737668055040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers k in A007691 for which A327153(k) = 0, that are not in A327165. Question: Is A323653 a subsequence of this sequence? See also conjecture in A348033. LINKS Table of n, a(n) for n=1..21. Index entries for sequences related to sigma(n) MATHEMATICA With[{s = DeleteCases[Map[ToExpression[#] &, Import["https://oeis.org/A007691/b007691.txt", "Data"]], _?(Length[#] == 0 &)][[All, -1]]}, Select[s[[1 ;; 45]], Function[k, NoneTrue[Divisors[k], # DivisorSigma[1, #] == k &]]]] (* Michael De Vlieger, Sep 28 2021, using b-file at A007691 *) CROSSREFS Cf. A348031 (complement in A007691). Cf. A327153, A327165, A348033. Sequence in context: A049359 A105711 A250491 * A224580 A224581 A224588 Adjacent sequences: A348029 A348030 A348031 * A348033 A348034 A348035 KEYWORD nonn AUTHOR Antti Karttunen, Sep 26 2021 STATUS approved

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

Last modified December 9 07:10 EST 2023. Contains 367689 sequences. (Running on oeis4.)