A134666 - OEIS

%I #9 Nov 14 2019 12:14:17

%S 1,1,2,2,1,4,1,5,4,4,3,6,1,3,4,5,1,9,1,19,8,9,3,5,6,7,16,13,26,20,1,6,

%T 8,6,13,23,20,6,9,33,10,11,14,18,15,13,32,23,23,18,12,20,26,21,16,17,

%U 7,11,20,15,1,10,17,14,13,26,21,16,24,13,21,27,18,14,16,21,38,19,12,26,13,23

%N Number of multiply perfect numbers (A007691) having 2^n as the highest power of 2.

%C It appears that a(n)>0 for all n. With the exception of n=2, a(n)=1 when n is p-1, where p is a Mersenne prime (A000043). Flammenkamp has an attractive graph of this sequence, including n for which there is incomplete data.

%H Achim Flammenkamp, <a href="http://wwwhomes.uni-bielefeld.de/achim/mpn.html">The Multiply Perfect Numbers Page</a>

%e a(2)=2 because only 28 and 2178540 have 2^2 as their highest power of 2.

%Y Cf. A134665 (highest power of 2 for each MPN).

%K nonn

%O 0,3

%A _T. D. Noe_, Nov 05 2007