# [seqfan] Re: Sharing no digit business (with building process)

Farideh Firoozbakht f.firoozbakht at sci.ui.ac.ir
Sat Apr 4 09:59:36 CEST 2009

```
S1: a(n) = smallest unseen positive integer sharing no digit with n.
S2: a(n) = smallest unseen positive integer sharing no digit with a(a(n)).

Two sequences S1 and S2 are different. S1(11)=20, S2(11)=12, ...
As you wrote, obviously S1 is finite. You have computed the first 200 terms
of S1.

Farideh Firoozbakht

Quoting David Wilson <dwilson at gambitcomm.com>:

> So a(n) = smallest unseen positive integer sharing no digit with n?
>
> 2 1 4 3 6 5 8 7 10 9 20 30 22 23 24 25 26 27 28 11 33 13 14 15 16 17
> 18 19 31 12 29 40 21 50 41 42 44 45 46 32 35 36 51 37 38 39 52 53 55 34
> 43 47 48 60 49 70 61 62 63 54 57 58 59 71 72 73 80 74 75 56 64 65 66 68
> 69 81 82 90 83 67 76 77 79 91 92 93 94 95 100 78 84 85 86 87 88 101 102
> 103 104 89 96 97 98 99 222 223 224 225 226 227 200 300 202 203 204 205
> 206 207 208 333 303 304 400 305 306 307 308 309 330 228 209 404 220 229
> 240 242 244 245 246 232 230 335 250 233 236 235 238 237 252 234 239 334
> 247 260 243 248 249 262 263 253 254 337 255 257 270 258 259 272 273 256
> 264 336 265 266 268 280 269 290 282 267 274 339 275 276 277 279 292 293
> 302 278 283 338 284 285 286 287 288 320 322 111
>
> This sequence of course finite ending at n = 123456788.
>
>>
> _______________________________________________
>
> Seqfan Mailing list - http://list.seqfan.eu/
>

----------------------------------------------------------------
University of Isfahan (http://www.ui.ac.ir)

```