A219544 Even multiply-perfect numbers divided by 2.

3, 14, 60, 248, 336, 4064, 15120, 16380, 261888, 1089270, 11784960, 16775168, 22766400, 71495424, 229909120, 689727360, 738152448, 4294934528, 7091219520, 15999197760, 21930739200, 25500590080, 33216860160

Offset: 1

Author

Jonathan Sondow, Nov 22 2012

Keywords

• nonn

Comments

Just as no odd perfect number is known, all known multiply-perfect numbers A007691 greater than 1 are even.

The subsequence of even perfect numbers divided by 2 is A133028.

The subsequence of even triperfects / 2 is A326051. - Antti Karttunen, Mar 20 2021

References

• R. K. Guy, Unsolved Problems in Number Theory, B2.

Crossrefs

Cf. A007691, A133028, A194771, A326051.

Formula

a(n) = A007691(n+1)/2.

a(n) = A194771(n+1)/4. [provided there are no odd multiperfect numbers > 1] - Antti Karttunen, Mar 20 2021