0,1

(+2)usigma(12)=(2+4)*(2+3)=30

Factorizations: 3*5*7, 3^2*5*7*11*13, 3*5*7^2*17*19, 3^2*5*7^2*11*13*17*19, 3^3*5*7*11*13*29*31, 3^3*5*7^2*11*13*17*19*29*31

A052396.

Sequence in context: A111647 A145621 A167779 this_sequence A028917 A145627 A096150

Adjacent sequences: A054859 A054860 A054861 this_sequence A054863 A054864 A054865

nonn

Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp)