A198585 The second odd number appearing in the Collatz sequence starting with A198584(n).

5, 5, 5, 85, 5, 341, 85, 5, 341, 85, 5, 341, 85, 5461, 5, 341, 21845, 85, 5461, 5, 341, 21845, 85, 5461, 5, 341, 21845, 85, 5461, 349525, 5, 341, 21845, 1398101, 85, 5461, 349525, 5, 341, 21845, 1398101, 85, 5461, 349525, 5, 341, 21845, 1398101, 85, 5461

Offset: 1

Author

T. D. Noe, Oct 28 2011

Keywords

• nonn

Comments

A198586 has the unique numbers appearing in this sequence.

Links

• T. D. Noe, Table of n, a(n) for n = 1..1009

Crossrefs

Cf. A079813, A198584, A198586.

Formula

a(n) = A079813(1 + (-1 + b(n))^2 + c(n))*(A198586(2*(1 + c(n))) - A198586(3 - 2*(b(n) - c(n)))) + A198586(3 - 2*(b(n) - c(n))) where b(n) = ceiling(sqrt(n)/sqrt(3)) and c(n) = (-1+n-3*(b(n)-1)^2) mod (2*b(n)-1). - Alan Michael Gómez Calderón, Jan 22 2025