A270108 This sequence O (made exclusively of odd numbers) becomes the sequence E (made exclusively of even numbers) by switching everywhere in O the two digits that are in contact with a comma. No repeated terms are allowed in O or E and we want O to be the lexicographically first such sequence.

1, 21, 23, 41, 25, 61, 27, 81, 29, 201, 203, 43, 45, 63, 47, 83, 49, 205, 401, 65, 67, 85, 69, 207, 601, 87, 89, 209, 801, 211, 213, 403, 405, 603, 407, 803, 409, 215, 411, 605, 607, 805, 609, 217, 611, 807, 809, 219, 811, 221, 223, 413, 415, 613, 417, 813

Offset

1,2

Comments

Here are the first terms of O and E, compared:

O = 1,21,23,41,25,61,27,81,201,203,43,45,63,47,83,401,205,...

E = 2,12,14,32,16,52,18,72,102,104,34,36,54,38,74,302,106,...

Links

Table of n, a(n) for n=1..56.

Cf. A270119.

Crossrefs

Sequence in context: A157676 A227948 A303718 * A335189 A304269 A302679

Adjacent sequences: A270105 A270106 A270107 * A270109 A270110 A270111

Keyword

nonn,base

Author

Eric Angelini and Lars Blomberg, Mar 11 2016

Status

approved