A223606 - OEIS

A223606

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

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: A230123 A049851 A353087 * A120147 A166499 A045533

Adjacent sequences: A223603 A223604 A223605 * A223607 A223608 A223609

KEYWORD

nonn,more

AUTHOR

Donovan Johnson, Mar 23 2013

STATUS

approved