67721
domain: N
Appears in sequences
- Strong pseudoprimes to base 40.at n=29A020266
- Strong pseudoprimes to base 61.at n=18A020287
- An L-tile is a 2 X 2 square with the upper 1 X 1 subsquare removed; no rotations are allowed. a(n) = number of tilings of a 4 X n rectangle using tiles that are either 1 X 1 squares or L-tiles.at n=11A025234
- Quasi-Carmichael numbers to exactly three bases.at n=21A257753
- Number of (6+1) X (n+1) 0..1 arrays with every 2 X 2 subblock ne-sw antidiagonal difference nondecreasing horizontally and nw+se diagonal sum nondecreasing vertically.at n=19A258559
- Semiprimes k = pq such that p^k == p (mod k) and q^k == q (mod k).at n=40A294169
- Expansion of Sum_{k>=0} x^k / Product_{j=1..k} (1 + j*x^j).at n=35A306702