A333523 Number of iterations of Reverse And Add needed to reach a number divisible by n (or 0 if such a number is never reached).

1, 1, 1, 1, 1, 1, 1, 1, 1, 61, 1, 3, 8, 34, 22, 8, 17, 2, 8, 119, 14, 1, 17, 7, 110, 7, 12, 33, 34, 158, 28, 12, 1, 60, 11, 12, 50, 79, 7, 129, 64, 13, 42, 1, 4, 89, 131, 8, 14, 81, 30, 19, 125, 12, 1, 88, 13, 33, 67, 232, 26, 27, 24, 123, 59, 1, 24, 59, 36, 206, 148, 12, 217, 90, 97

Offset: 1

Author

Daniel Starodubtsev, Mar 26 2020

Keywords

• nonn
• base

Comments

If n is a palindrome > 0, a(n) = 1. See A002113.

a(n) > 0 for n < 10000.

Examples

			a(12) = 3, because 12 takes 3 iterations (12 -> 33 -> 66 -> 132) to become 132, which is divisible by 12.
		

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002113, A016016, A056964.

Programs

PARI

radd(n) = fromdigits(Vecrev(digits(n)))+n; \\ A056964
a(n) = {my(i=1, k=n, x); while((x=radd(n)) % k, i++; n=x); i;} \\ Michel Marcus, Apr 11 2020