

A223606


Numbers n whose deficiency is 22: sigma(n)  2*n = 22.


2



23, 35, 39, 63, 116, 296, 848, 9536, 35456, 2118656, 537214976, 2148171776, 137444458496
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OFFSET

1,1


COMMENTS

Suggested by N. J. A. Sloane and Robert G. Wilson v.
a(14) > 10^12.
a(14) > 10^13.  Giovanni Resta, Mar 29 2013
a(14) > 10^18.  Hiroaki Yamanouchi, Aug 21 2018
Any term x of this sequence can be combined with any term y of A223612 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable.  Timothy L. Tiffin, Sep 13 2016


LINKS

Table of n, a(n) for n=1..13.


EXAMPLE

n = 9536. sigma(n)2*n = 22.


MATHEMATICA

Select[Range[1, 10^8], DivisorSigma[1, #]  2 # ==  22 &] (* Vincenzo Librandi, Sep 14 2016 *)


PROG

(PARI) for(n=1, 10^8, if(sigma(n)2*n==22, print1(n ", ")))
(MAGMA) [n: n in [1..9*10^6]  (SumOfDivisors(n)2*n) eq 22]; // Vincenzo Librandi, Sep 14 2016


CROSSREFS

Cf. A000203, A033879, A223612 (abundance 22).
Sequence in context: A146595 A230123 A049851 * A120147 A166499 A045533
Adjacent sequences: A223603 A223604 A223605 * A223607 A223608 A223609


KEYWORD

nonn,more


AUTHOR

Donovan Johnson, Mar 23 2013


STATUS

approved



