%I A135652
%S A135652 1,10,100,111,1110,11100
%N A135652 Divisors of 28 (the 2nd perfect number), written in base 2.
%C A135652 The number of divisors of the second perfect number is equal to 2*A000043(2)=A061645(2)=6.
%F A135652 a(n)=A018254(n), written in base 2. Also, for n=1 .. 6: If n<=(A000043(2)=3) 
               then a(n) is the concatenation of the digit "1" and n-1 digits "0" 
               else a(n) is the concatenation of A000043(2)=3 digits "1" and (n-1-A000043(2)) 
               digits "0".
%e A135652 The structure of divisors of 28 (See A018254)
%e A135652 ----------------------------------------------------------------------
%e A135652 n ... Divisor . Formula ....... Divisor written in base 2 ............
%e A135652 ----------------------------------------------------------------------
%e A135652 1)......... 1 = 2^0 ........... 1
%e A135652 2)......... 2 = 2^1 ........... 10
%e A135652 3)......... 4 = 2^2 ........... 100 .... (The 2nd superperfect number)
%e A135652 4)......... 7 = 2^3 - 2^0 ..... 111 .... (The 2nd Mersenne prime)
%e A135652 5)........ 14 = 2^4 - 2^1 ..... 1110
%e A135652 6)........ 28 = 2^5 - 2^2 ..... 11100... (The 2nd perfect number)
%Y A135652 For more information see A018254 (Divisors of 28). Cf. A000043, A000079, 
               A000396, A000668, A019279, A061645, A061652.
%Y A135652 Sequence in context: A154810 A099820 A167502 this_sequence A035504 A072366 
               A119082
%Y A135652 Adjacent sequences: A135649 A135650 A135651 this_sequence A135653 A135654 
               A135655
%K A135652 base,nonn,fini,full
%O A135652 1,2
%A A135652 Omar E. Pol (info(AT)polprimos.com), Feb 23 2008, Mar 03 2008