|
| |
|
|
A112386
|
|
Smallest prime obtained by appending one or more 1's to n.
|
|
1
|
|
|
|
11, 211, 31, 41, 511111, 61, 71, 811, 911, 101, 1111111111111111111, 121111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111, 131, 14111111111, 151, 16111, 1711111111, 181, 191, 2011, 211, 22111, 2311, 241
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Number of appended ones: 1,2,1,1,5,1,1,2,2,1,17,1,1,2,7,1,2,1,1,2,2,67,2,4,217,3,2,1,6,1,.., . - Robert G. Wilson v, Dec 05 2005
|
|
|
LINKS
|
Table of n, a(n) for n=1..24.
|
|
|
EXAMPLE
|
a(5) = 511111 because 51, 511, 5111 and 51111 are not primes.
|
|
|
MATHEMATICA
|
f[n_] := Block[{k = 1, e = Floor[Log[10, n] + 1]}, While[ !PrimeQ[n*10^k + (10^k - 1)/9], k++ ]; n*10^k + (10^k - 1)/9]; Array[f, 24] (* Robert G. Wilson v *)
Table[SelectFirst[Table[FromDigits[PadRight[IntegerDigits[k], n, 1]], {n, IntegerLength[k]+1, 250}], PrimeQ], {k, 25}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Nov 30 2017 *)
|
|
|
CROSSREFS
|
Sequence in context: A280072 A157691 A196944 * A160693 A167442 A249974
Adjacent sequences: A112383 A112384 A112385 * A112387 A112388 A112389
|
|
|
KEYWORD
|
nonn,base
|
|
|
AUTHOR
|
Michel Dauchez (mdzdm(AT)yahoo.fr), Dec 04 2005
|
|
|
EXTENSIONS
|
Edited, corrected and extended by Robert G. Wilson v, Dec 05 2005
|
|
|
STATUS
|
approved
|
| |
|
|
