The sequence contains no further entries between 294 and 1600. - R. J. Mathar, May 26 2011
Table of n, a(n) for n=1..12.
a(7) is 25 because the 25th multiply-perfect number A007691(25)=137438691328 is also the 7th perfect number A000396(7).
Cf. A000396, A007691.
Sequence in context: A233043 A231099 A062252 * A147791 A169647 A072467
Adjacent sequences: A153797 A153798 A153799 * A153801 A153802 A153803
Omar E. Pol, Jan 13 2009