69020
domain: N
Appears in sequences
- a(n) = n*(n + 1)*(3*n + 1).at n=28A027903
- Numbers n such that 69*2^n-1 is prime.at n=58A050560
- a(n) = Sum_{k=1..n} k*(prime(k) - k).at n=33A110477
- Number of ways to place 2 queens on an n X n chessboard so that they attack each other.at n=34A144945
- Govindarajan's triangle beta arising in enumeration of multi-dimensional partitions, read by rows.at n=19A216808
- a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n-1,2*k) * a(k).at n=16A352044