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!)
A369886 a(n) is the least positive integer that can be expressed as +- 1 +- 2 +- 3 +- ... +- n in exactly n ways, or -1 if no such integer exists. 0
1, -1, -1, -1, -1, -1, 6, 16, 25, 35, -1, 56, -1, -1, 96, -1, -1, 145, -1, -1, -1, 225, -1, -1, -1, -1, 348, -1, -1, -1, -1, 496, -1, -1, -1, -1, -1, 707, -1, -1, -1, -1, -1, -1, -1, 1045, -1, -1, -1, -1, -1, -1, -1, 1447, -1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,7
LINKS
EXAMPLE
a(7) = 6: 6 = + 1 + 2 + 3 - 4 + 5 + 6 - 7
= - 1 + 2 - 3 + 4 + 5 + 6 - 7
= + 1 + 2 + 3 + 4 - 5 - 6 + 7
= - 1 + 2 + 3 - 4 + 5 - 6 + 7
= + 1 - 2 - 3 + 4 + 5 - 6 + 7
= + 1 - 2 + 3 - 4 - 5 + 6 + 7
= - 1 - 2 - 3 + 4 - 5 + 6 + 7.
CROSSREFS
Sequence in context: A114222 A348229 A275641 * A171440 A031220 A011536
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Feb 04 2024
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 April 23 18:16 EDT 2024. Contains 371916 sequences. (Running on oeis4.)