login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A180968 The only integers that cannot be partitioned into a sum of six positive squares. 3
1, 2, 3, 4, 5, 7, 8, 10, 11, 13, 16, 19 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
From R. J. Mathar, Sep 11 2012: (Start)
Not the sum of 7 positive squares: 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 14, 17, 20.
Not the sum of 8 positive squares: 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 13, 15, 18, 21.
Not the sum of 9 positive squares: 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 13, 14, 16, 19, 22.
Not the sum of 10 positive squares: 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 14, 15, 17, 20, 23. (End)
REFERENCES
Dubouis, E.; L'Interm. des math., vol. 18, (1911), pp. 55-56, 224-225.
Grosswald, E.; Representation of Integers as Sums of Squares, Springer-Verlag, New York Inc., (1985), pp.73-74.
LINKS
Gordon Pall, On Sums of Squares, The American Mathematical Monthly, Vol. 40, No. 1, (January 1933), pp. 10-18.
FORMULA
Let B be the set of integers {1,2,4,5,7,10,13}. Then, for s>=6, every integer can be partitioned into a sum of s positive squares except for 1,2,...,s-1 and s+b where b is a member of the set B [Dubouis].
EXAMPLE
As the sixth integer which cannot be partitioned into a sum of six positive squares is 7, we have a(6)=7.
MATHEMATICA
s=6; B={1, 2, 4, 5, 7, 10, 13}; Union[Range[s-1], s+B]//Sort
CROSSREFS
Cf. A047701 (not the sum of 5 squares)
Sequence in context: A025199 A213858 A277992 * A191847 A321290 A274337
KEYWORD
fini,full,nonn
AUTHOR
Ant King, Sep 30 2010
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 11:59 EDT 2024. Contains 371254 sequences. (Running on oeis4.)