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

1,1

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.

Links

Table of n, a(n) for n=1..23.

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

Crossrefs

Cf. A007691, A133028, A194771, A326051.

Sequence in context: A151235 A151236 A006224 * A131262 A171499 A006502

Adjacent sequences: A219541 A219542 A219543 * A219545 A219546 A219547

Keyword

nonn

Author

Jonathan Sondow, Nov 22 2012

Status

approved