OFFSET
1,1
COMMENTS
Sum of n-th even perfect number and n-th even superperfect number.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..15
FORMULA
a(n) = 2^(2*A000043(n) - 1). Also, a(n) = 2^A133033(n), if there are no odd perfect numbers. Also, a(n) = A000396(n) + A019279(n), if there are no odd perfect and odd superperfect numbers. Also, a(n) = A000396(n) + A061652(n), if there are no odd perfect numbers, then we can write: perfect number A000396(n) = a(n) - A061652(n).
EXAMPLE
MATHEMATICA
2^(2 * MersennePrimeExponent[Range[10]] - 1) (* Amiram Eldar, Oct 17 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Apr 13 2008
STATUS
approved