

A233416


cperfect numbers.


3




OFFSET

1,1


COMMENTS

A number k is called a cperfect number if the sum of its proper cdivisors equals k.
For the definition of a cdivisor of an integer, see comment in A124771.
From Charlie Neder, Jan 17 2019: (Start)
Sequence in binary: 1011, 1000111, 11100010, 111001011100, 100001000001111, 100010111000111100011, 10010000000101000110011, 100001111110010100110011...
Next term > 10^7. (End)


LINKS

Table of n, a(n) for n=1..8.
Index entries for sequences related to binary expansion of n


FORMULA

A233394(a(n))=2*a(n).


EXAMPLE

For n=11 which is a concatenation of binary parts (10)(1)(1); we have proper positive cdivisors 1, 2, 3, and 5, the sum of which is 11, so 11 is in the sequence.


CROSSREFS

Cf. A124771, A233394.
Sequence in context: A089720 A174202 A139850 * A174822 A201790 A268985
Adjacent sequences: A233413 A233414 A233415 * A233417 A233418 A233419


KEYWORD

nonn,more,base


AUTHOR

Vladimir Shevelev and Peter J. C. Moses, Dec 09 2013


EXTENSIONS

a(6)a(8) from Charlie Neder, Jan 17 2019


STATUS

approved



