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Even superperfect numbers written in base 2.
1

%I #3 Mar 30 2012 17:33:53

%S 10,100,10000,1000000,1000000000000,10000000000000000,

%T 1000000000000000000,1000000000000000000000000000000

%N Even superperfect numbers written in base 2.

%C Also, superperfect numbers (A019279) written in base 2 (If there are no odd perfect numbers).

%C Also, concatenation of "1" and A090748(n) digits "0".

%C The number of digits of a(n) is equal to A000043(n) and also equal to the number of digits of n-th Mersenne prime written in base 2 (see A117293, A135650).

%e a(3)=10000 because the 3rd even superperfect number A061652(3)=16 and 16 written in base 2 is equal to 10000.

%Y Cf. A000043, A000668, A019279, A061652, A090748, A117293, A135650.

%K base,nonn

%O 1,1

%A _Omar E. Pol_, Feb 23 2008