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A034683 Unitary abundant numbers (usigma(n)>2n). 30
30, 42, 66, 70, 78, 102, 114, 138, 150, 174, 186, 210, 222, 246, 258, 282, 294, 318, 330, 354, 366, 390, 402, 420, 426, 438, 462, 474, 498, 510, 534, 546, 570, 582, 606, 618, 630, 642, 654, 660, 678, 690, 714, 726, 750, 762, 770, 780, 786, 798, 822, 834 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a term n in the sequence ends in neither 0 nor 5, then 10*n is also in the sequence. - Lekraj Beedassy, Jun 11 2004

REFERENCES

C. Sung, Mathematical Buds, "Unitary Divisors", Chap. V pp. 42-67, Ed. H. D. Ruderman, Mu Alpha Theta OK 1978.

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

MAPLE

isA034683 := proc(n)

    is(A034448(n) > 2*n) ;

end proc:

for n from 1 do

    if isA034683(n) then

        print(n);

    end if;

end do: # R. J. Mathar, Nov 10 2014

MATHEMATICA

usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])];

Select[Range[1000], usigma[#] > 2#&] (* Jean-Fran├žois Alcover, Mar 23 2020, after Giovanni Resta in A034448 *)

CROSSREFS

Cf. A034444, A034448, A129487.

Sequence in context: A053858 A075819 A306217 * A328328 A302574 A087248

Adjacent sequences:  A034680 A034681 A034682 * A034684 A034685 A034686

KEYWORD

nonn

AUTHOR

Erich Friedman

STATUS

approved

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Last modified November 26 01:22 EST 2020. Contains 338631 sequences. (Running on oeis4.)