A158320 a(1)=0, a(n) is the smallest nonprime > (n-1)^smallest digit of a(n-1).

0, 4, 18, 4, 258, 26, 38, 344, 513, 10, 4, 14642, 14, 14, 15, 16, 18, 18, 20, 4, 160002, 4, 234257, 530, 4, 390626, 4, 531442, 30, 4, 810001, 4, 1048577, 4, 1336338, 36, 46657, 1874162, 39, 59320

Offset

1,2

Links

Table of n, a(n) for n=1..40.

Example

0, 4(>1=1^0), 20(>18=2^4), 4(>1=3^0), 258(>256=4^4), 26(>25=5^2), 38(>36=6^2), 344(>343=7^3), 513(>512=8^3), 10(>9=9^1), 4(>1=10^1), 14642(>14641=11^4), 14(>12=12^1), 14(>13=13^1), 15(>14=14^1), 16(>15=15^1), 18(>16=16^1), 18(>17=17^1), 20(>18=18^1), 4(>1=19^0), ?(>160000=20^4)

Mathematica

nxt[{n_, a_}]:=Module[{k=n^Min[IntegerDigits[a]]+1}, While [PrimeQ[k], k++]; {n+1, k}]; Transpose[NestList[nxt, {1, 0}, 40]][[2]] (* Harvey P. Dale, Apr 17 2015 *)

Crossrefs

Cf. A000027, A141468.

Sequence in context: A246133 A205014 A204936 * A342153 A341800 A236563

Adjacent sequences: A158317 A158318 A158319 * A158321 A158322 A158323

Keyword

nonn,base,less

Author

Juri-Stepan Gerasimov, Mar 16 2009

Extensions

Corrected (a(3) replaced by 18, duplicate of a(20) removed) and extended by R. J. Mathar, May 19 2010

Definition corrected by Harvey P. Dale, Apr 17 2015

Status

approved