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 A082731 a(n) = smallest number k such that A033880(k)= n, or 0 if no such number exists, where A033880 is the abundance of k. 2
 6, 0, 20, 18, 12, 0, 8925, 196, 56, 0, 40, 0, 24, 0, 272, 0, 550, 100, 208, 36, 176, 0, 1312, 0, 112, 0, 80, 0, 48, 0, 945, 15376, 572, 0, 928, 0, 2205, 0, 5696, 162, 736, 1352, 9555, 0, 350, 0, 490, 0, 60, 0, 416, 72, 352, 0, 90, 0, 84, 0, 160, 968, 96, 0, 24704, 0, 108, 200 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Caution: so far a(n)=0 only indicates no k<3*10^6 exists; nonexistence is not proved. - R. J. Mathar, Jul 26 2007 LINKS F. Firoozbakht, M. F. Hasler, Variations on Euclid's formula for Perfect Numbers, JIS 13 (2010) #10.3.1 MAPLE A082731 := proc(n) local k; k := 1 ; while numtheory[sigma](k)-2*k <> n do k := k+1 ; if k = 3000000 then RETURN(0) ; fi ; od ; RETURN(k) ; end: seq(A082731(n), n=0..200) ; # R. J. Mathar, Nov 07 2016 CROSSREFS Cf. A082730. Sequence in context: A167356 A219540 A292497 * A272673 A167357 A064381 Adjacent sequences:  A082728 A082729 A082730 * A082732 A082733 A082734 KEYWORD nonn AUTHOR Amarnath Murthy, Apr 14 2003 EXTENSIONS More terms from R. J. Mathar, Jul 26 2007 STATUS approved

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Last modified August 13 22:46 EDT 2020. Contains 336473 sequences. (Running on oeis4.)