Expected solvable difficulty
1sample+: experienced solvers
keywords+: most solvers
OEIS is the On-Line Encyclopedia of Integer Sequences. This level was inspired by a video series of OEIS graphs on Numberphile. Questions are chosen from sequences in the OEIS database labeled with
nice, and 3 consecutive numbers are chosen from the sequence so that no other sequence have the same subsequence. Also, the first sample question is chosen such that OEIS does not show up on the first page when searching for the sequence ID. (The search result may change now as time passes.)
Besides, the last sample question is written in the form of the OEIS logo.
0, 1, 3, 6, 2, 7, ⋮ 13, ⋮ 20, 23, 12, 10, 22, 11, 21,
Expected thought process
Find out the question is a sequence in OEIS, and look up the sequence ID.