

A181597


(N\{4})perfect numbers, i.e., numbers m for which sigma(m)4 = 2m, if 4m, otherwise sigma(m) = 2m.


2




OFFSET

1,1


COMMENTS

Or union of {6}, nearperfect numbers m (cf. A181595) for which d(m)=4, and all odd perfect numbers (if they exist). Note that (N\{2})perfect numbers are numbers for which sigma(m)2=2m, if m is even, and sigma(m)=2m, if m is odd. They are all even numbers of A045768 and all odd perfect numbers (if they exist).


LINKS

Table of n, a(n) for n=1..10.


EXAMPLE

88 is in the sequence since sigma(88) = 180 and 180  4 = 2*88.


CROSSREFS

Cf. A000396, A005101, A005820, A088832, A118372, A153501, A181595, A181596.
Sequence in context: A054883 A005402 A128953 * A002898 A003613 A099767
Adjacent sequences: A181594 A181595 A181596 * A181598 A181599 A181600


KEYWORD

nonn,more


AUTHOR

Vladimir Shevelev, Nov 01 2010, Nov 03 2010


EXTENSIONS

Invalid term removed and a(8)a(10) from Donovan Johnson, Sep 14 2013


STATUS

approved



