login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A100832 Amenable numbers: n such that there exists a multiset of integers (s(1), ..., s(n)) whose size, sum and product are all n. 0
1, 5, 8, 9, 12, 13, 16, 17, 20, 21, 24, 25, 28, 29, 32, 33, 36, 37, 40, 41, 44, 45, 48, 49, 52, 53, 56, 57, 60, 61, 64, 65, 68, 69, 72, 73, 76, 77, 80, 81, 84, 85, 88, 89, 92, 93, 96, 97, 100, 101, 104, 105, 108, 109, 112, 113, 116, 117, 120, 121, 124, 125, 128, 129, 132 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Essentially the same as A042948.

The set {s(i)} is closed under multiplication. - Lekraj Beedassy, Jan 21 2005

REFERENCES

O. P. Lossers, Solution to problem 10454, "Amenable Numbers", Amer. Math. Monthly Vol. 105 No. 4 April 1998 MAA Washington DC.

LINKS

Table of n, a(n) for n=1..65.

Eric Weisstein's World of Mathematics, Amenable Number

Wikipedia, Amenable number

FORMULA

Consists of the numbers n == 0 or 1 (mod 4), excluding n=4.

a(n)=a(n-1)+a(n-2)-a(n-3), n>4. G.f.: x*(1+3*x)*(1+x-x^2)/(1-x-x^2+x^3). [Colin Barker, Jan 26 2012]

EXAMPLE

5 and 8, for instance, are in the sequence because we have 5=1-1+1-1+5=1*(-1)*1*(-1)*5 and 8=1-1+1-1+1+1+2+4=1*(-1)*1*(-1)*1*1*2*4.

CROSSREFS

Cf. A014601.

Sequence in context: A191977 A101079 A066812 * A034812 A066467 A180244

Adjacent sequences:  A100829 A100830 A100831 * A100833 A100834 A100835

KEYWORD

nonn

AUTHOR

Lekraj Beedassy, Jan 07 2005

EXTENSIONS

More terms from David W. Wilson, Jan 24 2005

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified December 22 05:04 EST 2014. Contains 252328 sequences.