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!)
A002243 Numbers that are not the sum of 3 distinct triangular numbers. 5
1, 2, 3, 5, 6, 8, 12, 15, 20, 23, 33, 78 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
Complement[Range[100], Union[Total/@Subsets[Accumulate[Range[0, 12]], {3}]]] (* Harvey P. Dale, Sep 02 2014 *)
PROG
(PARI) is(n)=for(c=ceil((sqrt(24*n-15)+3)/6), (sqrt(8*n-7)-1)/2, my(t=n-c*(c+1)/2); for(b=sqrtint(t-1)+1, min((sqrt(8*n+1)-1)/2, c-1), if(ispolygonal(t-b*(b+1)/2, 3), return(0)))); 1
select(is, [1..100]) \\ Charles R Greathouse IV, Nov 25 2014
CROSSREFS
Sequence in context: A002384 A096176 A330748 * A094763 A338916 A125559
KEYWORD
fini,full,nonn
AUTHOR
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 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)