# [seqfan] Re: Question regarding A069570

Jeremy Gardiner jeremy.gardiner at btinternet.com
Thu Jun 17 13:34:17 CEST 2010

```Aha! Thanks.

By the way, I calculate the sequence "Numbers in which the n-th digit is
either a divisor or a non-zero multiple of n" counting digits from the left,
as follows:

1,2,3,4,5,6,7,8,9,11,12,14,16,18,21,22,24,26,28,31,32,34,36,38,41,42,44,46,4
8,51,52,54,56,58,61,62,64,66,68,71,72,74,76,78,81,82,84,86,88,91,92,94,96,98
,111,113,116,119,121,123,126,129,141,143,146,149,161,163,166,169,181,183,186
,189,211,213,216,219,221,223,226,229,241,243,246,249,261,263,266,269,281,283
,286,289,311,313,316,319,321,323,326,329,341,343,346,349,361,363,366,369,381
,383,386,389,411,413,416,419,421,423,426,429,441,443,446,449,461,463,466,469
,481,483,486,489,511,513,516,519,521,523,526,529,541,543,546,549,561,563,566
,569,581,583,586,589,611,613,616,619,621,623,626,629,641,643,646,649,661,663
,666,669,681,683,686,689,711,713,716,719,721,723,726,729,741,743,746,749,761
,763,766,769,781,783,786,789,811,813,816,819,821,823,826,829,841,843,846,849
,861,863,866,869,881,883,886,889,911,913,916,919,921,923,926,929,941,943,946
,949,961,963,966,969,981,983,986,989

(Not in the OEIS) - is this "interesting"?

Jeremy

On 17/6/10 11:48, "Andrew Weimholt" <andrew.weimholt at gmail.com> wrote:

> On Thu, Jun 17, 2010 at 3:17 AM, Jeremy Gardiner
> <jeremy.gardiner at btinternet.com> wrote:
>>
>> My interpretation is that,
>>
>> 1st digit is either a divisor or a multiple of 1,
>> 2nd digit is either a divisor or a multiple of 2,
>> 3rd digit is either a divisor or a multiple of 3, etc.
>>
>> e.g. Why are 13 and 122 in the sequence, among others?
>>
>
> It appears that by "1st digit", the author means "least significant digit",
> so with 13, the first digit is 3 and the second is 1.
>
> There is a typo in the sequence:  ...19, 18, 19,... should be
> ...17, 18, 19,...
>
> The title should be reworded to something like
> "Numbers in which the n-th least significant digit is either a divisor
> or a non-zero multiple of n."
>
> (added "least significant" and "non-zero")
>
> Sequences A069571 through A069574 should include the same
> clarifications in their titles.
>
> Andrew
>

```