A109138 - OEIS

%I #13 Oct 12 2019 12:22:55

%S 6,8,12,14,18,20,24,32,44,62,80,102,128,168,192,200,314,348,702

%N Numbers n such that 2^n + 2 is an admirable number (A111592).

%C For k > 1, A000978(k)+1 is a member. Are there any others? - _David Wasserman_, May 28 2008

%C No more terms below 1064. - _Amiram Eldar_, Oct 12 2019

%e a(3)=12 because 2^12 + 2 = 4098 and 1+2+3+683+1366+2049-6 = 4098.

%t fQ[n_] := Block[{d = Most[ Divisors[n]], k = 1}, l = Length[d]; s = Plus @@ d; While[k < l && s - 2d[[k]] > n, k++ ]; If[k > l || s != n + 2d[[k]], False, True]]; Do[ If[ fQ[2^n + 2], Print[n]], {n, 200}] (* _Robert G. Wilson v_, Aug 30 2005 *)

%Y Cf. A000978.

%K nonn,more

%O 1,1

%A _Jason Earls_, Aug 18 2005

%E More terms from _David Wasserman_, May 28 2008

%E a(19) from _Amiram Eldar_, Oct 12 2019