66938

Appears in sequences

• Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having exactly k entries that are midpoints of 321 patterns (0 <= k <= n-2 for n >= 2; k=0 for n=1).at n=34A145879
• Triangle T(n,k), read by rows, given by (1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, ...) DELTA (0, 0, 1, 1, 2, 2, 3, 3, 4, 4, ...) where DELTA is the operator defined in A084938.at n=50A202992
• Semiprimes p such that next semiprime after p is p+20.at n=18A217335
• Positive numbers whose square starts and ends with exactly 44, and no 444.at n=32A348831