309406

Appears in sequences

• Number of permutations P of {1,2,...,n} such that P(1)=1 and |P^-1(i+1)-P^-1(i)| equals 1 or 2 for i=1,2,...,n-1.at n=32A038718
• Position of 1/n in the ordering of the rationals given by application of the map t -> (1+t,-1/t), cf. A226130.at n=10A226274
• Numbers m such that gcd(s1,s2) = number of the Collatz iterations of m where s1 is the sum of the odd terms and s2 the sum of the even terms in the Collatz trajectory.at n=34A281195