20210

Appears in sequences

• In the list of divisors of n (in base 3), each digit 0-2 appears equally often.at n=10A045811
• Łukasiewicz word for each rooted plane tree (interpretation e in Stanley's exercise 19) encoded by A014486 (or A063171), with the last leaf implicit, i.e., these words are given without the last trailing zero, except for the null tree which is encoded as 0.at n=34A071153
• Binary numbers with 2 replacing 1 in odd positions.at n=22A095914
• Numbers k such that N*2^k - 1 is prime where N = 9999999999999999999999988888888888888888887777777777777777766666666666665555555555544444443333322211.at n=5A098466
• 5-Smith numbers.at n=3A103126
• Numbers n such that sigma(n) = 2*(n-reversal(n)).at n=7A135242
• Number of partitions p of n not including round(mean(p)) as a part. (This is "Mathematica round"; for round(x) defined as floor(x + 1/2), see A241734.)at n=41A241339
• Number of partitions p of n such that round(mean(p)) is not a part of p; here, round(x) means floor(x + 1/2).at n=41A241734
• a(n) = number of distinct words arising in Post's tag system {00, 1101} applied to the word (100)^n , or a(n) = -1 if this word has an unbounded trajectory.at n=36A302202