This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A122839 Numbers such that Sigma(m)*UnitarySigma(m)= k*UnitaryPhi(m)^2, for some integer k. 1
 1, 2, 3, 6, 14, 15, 30, 35, 42, 60, 70, 78, 105, 190, 210, 312, 357, 418, 570, 714, 910, 1045, 1254, 1428, 2090, 2730, 3135, 3640, 4522, 4674, 5278, 6270, 10659, 10920, 12441, 13566, 14630, 15834, 16770, 18696, 20026, 21318, 23374, 24871, 24882, 24969, 25070, 25714, 27170 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Terms which are squarefree appear on A121556. LINKS MAPLE isA122839 := proc(m)     A047994(m) ;     modp(numtheory[sigma](m)*A034448(m), %^2) = 0 ; end proc: for m from 1 do     if isA122839(m) then         printf("%a, \n", m) ;     end if; end do: # R. J. Mathar, Sep 04 2018 PROG (PARI) isok(m) = ((sigma(m)*usigma(m)) % uphi(m)^2) == 0; \\ Michel Marcus, Jan 24 2019 CROSSREFS Cf. A034448, A047994, A121556. Sequence in context: A146000 A134737 A030733 * A258077 A121556 A123041 Adjacent sequences:  A122836 A122837 A122838 * A122840 A122841 A122842 KEYWORD nonn AUTHOR Yasutoshi Kohmoto, Oct 23 2006 EXTENSIONS More terms from Michel Marcus, Jan 24 2019 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 December 10 23:29 EST 2019. Contains 329910 sequences. (Running on oeis4.)