220020

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=6A071152
• Numbers k such that k*((2^61-1)^2) - 1 and k*((2^61-1)^2) + 1 are twin primes.at n=31A099229
• Numbers n such that n*((2^61-1)^3) - 1 and n*((2^61-1)^3) + 1 are twin primes.at n=14A099230
• Numbers k such that k and k^2 use only the digits 0, 2, 4 and 8.at n=34A136908
• Numbers k such that k^2 has only digits 0, 4 and 8.at n=38A202170