2020202020

Appears in sequences

• Łukasiewicz words for the rooted plane binary trees (interpretation d in Stanley's exercise 19) 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=23A071152
• Kaprekar numbers (A006886) that are divisible by the sum of their digits.at n=37A382165