60248

Appears in sequences

• Numbers k such that k^2 divides 15^k-1.at n=32A128395
• Numbers k of the form abs(a - b + c - d) such that k^4 equals the concatenation of a//b//c//d and numbers k,b,c,d have the same number of digits.at n=23A260193
• Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 81", based on the 5-celled von Neumann neighborhood.at n=7A270099
• Birooted trees: number of unlabeled trees with n nodes rooted at 2 indistinguishable roots.at n=12A303833