A094150 Number of iterations of the sum of digits of the divisors of R(n) needed to reach 15, where R(n) = A002275.
5, 13, 12, 3, 11, 10, 15, 3, 14, 3, 5, 18, 13, 4, 18, 18, 5, 2, 4, 3, 12, 10, 21, 12, 18, 16, 11, 19, 20, 4, 6, 12, 13, 6, 6, 5, 3, 16, 5, 12, 12, 11, 18, 16, 18, 17, 12, 5, 12, 12, 18, 19, 14, 4, 5, 12, 18, 10, 16, 6, 13, 17, 21, 19, 6, 13, 19, 4, 3, 7, 15, 10, 21, 4, 18, 3, 5, 20, 11, 18
Offset: 2
Examples
a(9)=3 because 111111111 -> 151 -> 8 -> 15. a(1) does not exist because 1 -> 1 and never reaches 15.
Extensions
More terms from David Wasserman, May 22 2007