A124116 a(n) is the smallest positive integer such that a(n)+10^k is prime for 1 <= k <= n.

1, 1, 9, 9, 559, 847, 15127, 54621, 54621, 5893321, 167459299, 3595903759, 3595903759, 1040749968601, 688840705177051, 430442854738298199

Offset

1,3

Comments

Infinite under Dickson's conjecture. - Charles R Greathouse IV, Jan 26 2012

Links

Table of n, a(n) for n=1..16.

Carlos Rivera, Puzzle 554. P+10^n, The Prime Puzzles and Problems Connection.

Formula

a(n) == 0 (mod 7) for n > 5.

Example

a(5) = 559 because 569, 659, 1559, 10559 and 100559 are all prime.

Crossrefs

Sequence in context: A171738 A309316 A366930 * A213154 A226050 A058200

Adjacent sequences: A124113 A124114 A124115 * A124117 A124118 A124119

Keyword

nonn,hard,more

Author

Anton Vrba (antonvrba(AT)yahoo.com), Nov 28 2006

Extensions

a(12)-a(13) from Michael S. Branicky, Sep 19 2022

a(14)-a(16) from Jens Kruse Andersen, Sep 23 2022

Status

approved