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

1,10

Comments

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

a(n) > 0 for n < 10000.

Links

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

Example

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

Prog

(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

Crossrefs

Cf. A002113, A016016, A056964.

Sequence in context: A003928 A065247 A058930 * A249909 A241601 A132096

Adjacent sequences: A333520 A333521 A333522 * A333524 A333525 A333526

Keyword

nonn,base

Author

Daniel Starodubtsev, Mar 26 2020

Status

approved