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The large terms, for example at n=41, correspond to the perfect numbers A000396 in A007691. See A134666 for the number of multiply perfect numbers having a given highest exponent of 2.
T. D. Noe, Table of n, a(n) for n=1..5000 (using Flammenkamp's data)
Achim Flammenkamp, The Multiply Perfect Numbers Page
Sequence in context: A070667 A245349 A122416 * A271832 A063260 A271859
Adjacent sequences: A134662 A134663 A134664 * A134666 A134667 A134668
T. D. Noe, Nov 05 2007