1,1

a(9) = 81239400. Sigma(81239400) = 300690390 = 2*3*5*7*11*13*17*19*31 (9 distinct prime factors).

Cf. A000203, A001221.

Sequence in context: A039909 A009551 A006924 this_sequence A006867 A019536 A129949

Adjacent sequences: A152559 A152560 A152561 this_sequence A152563 A152564 A152565

nonn

Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 09 2008