27681

Appears in sequences

• Decimal part of a(n)^(1/6) starts with reversal of its integer part: first term of runs.at n=4A034312
• Reversion of rooted trees A000081.at n=21A050395
• Integers n such that 10^n - 23 is a prime number.at n=9A108328
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (-1, 1, -1), (0, 1, -1), (1, 0, 0)}.at n=11A148142
• Numbers whose Collatz trajectories cross their initial values a record number of times.at n=24A319738
• Semiprimes k such that k is congruent to 5 modulo k's index in the sequence of semiprimes.at n=4A357023