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%I #17 Jan 12 2021 06:24:50
%S 6,0,20,18,12,0,8925,196,56,0,40,0,24,0,272,0,550,100,208,36,176,0,
%T 1312,0,112,0,80,0,48,0,945,15376,572,0,928,0,2205,0,5696,162,736,
%U 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
%N a(n) is the smallest number k such that A033880(k)= n, or 0 if no such number exists, where A033880 is the abundance of k.
%C Caution: so far a(n)=0 only indicates no k < 3*10^6 exists; nonexistence is not proved. - _R. J. Mathar_, Jul 26 2007
%C For each term listed as 0 in the Data section, there is no such k < 10^14. - _Jon E. Schoenfield_, Jan 12 2021
%H F. Firoozbakht and M. F. Hasler, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL13/Hasler/hasler2.html">Variations on Euclid's formula for Perfect Numbers</a>, JIS 13 (2010) #10.3.1.
%p 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
%Y Cf. A082730.
%K nonn
%O 0,1
%A _Amarnath Murthy_, Apr 14 2003
%E More terms from _R. J. Mathar_, Jul 26 2007
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