A228092 Lexicographically first sequence of nonprime terms (with no duplicates) that turns into a sequence of prime terms (with no duplicates) by applying the "comma-permutation" simultaneously at every comma. [The "comma-permutation" is explained in the Comments section.]

1, 21, 12, 32, 33, 91, 14, 72, 111, 15, 92, 321, 301, 102, 322, 721, 901, 702, 931, 312, 332, 942, 152, 153, 74, 75, 34, 93, 703, 711, 121, 731, 132, 762, 361, 932, 972, 171, 741, 951, 154, 704, 104, 912, 981, 161, 362, 781, 371, 372, 992, 3002, 3012, 1011, 782, 1022, 7021, 993, 112, 3031, 994, 323

Offset

1,2

Comments

The "comma-permutation" swaps the last digit of a(n) and the first digit of a(n+1) for every n. For instance [2016,2017] becomes [2012,6017] and [2016,2017,2018] turns into [2012,6012,7018].

The sequence is always extended with the smallest integer not yet present that does not lead to a contradiction.

No term ends in "0" as this "0" would start a term of the prime sequence.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000 (first 205 terms from Eric Angelini and Jean-Marc Falcoz)

Rémy Sigrist, PARI program for A228092

Example

Under the "comma-permutation" the nine nonprime terms [1,21,12,32,33,91,14,72,111,15] become the primes [2,11,13,23,29,31,17,41,211].

Prog

(PARI) See Links section.

Crossrefs

Cf. A274408.

Sequence in context: A260527 A260529 A166033 * A071262 A083466 A307312

Adjacent sequences: A228089 A228090 A228091 * A228093 A228094 A228095

Keyword

nonn,base

Author

Eric Angelini and Jean-Marc Falcoz, Jun 17 2016

Status

approved