A277383 Each even integer k is followed by k odd integers.

0, 2, 1, 3, 4, 5, 7, 9, 11, 6, 13, 15, 17, 19, 21, 23, 8, 25, 27, 29, 31, 33, 35, 37, 39, 10, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 12, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 14, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 16, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133

Offset

1,2

Comments

The sequence starts with a(1) = 0 and was always extended with the smallest nonnegative integer not yet present that does not lead to a contradiction.

Links

Jean-Marc Falcoz, Table of n, a(n) for n = 1..7162

Example

As a(1) = 0, a(2) cannot be an odd term: thus a(2) = 2 (the smallest available nonnegative even integer); now as a(3) and a(4) must be odd integers we have a(3) = 1 and a(4) = 3 (again, the smallest available nonnegative odd integers); now a(5) = 4, forcing the next 4 integers to be odd, thus a(6) = 5, a(7) = 7, a(8) = 9 and a(9) = 11; etc.

Mathematica

Table[Prepend[2 Range[# (# + 1) + 1, # (# + 1) + 2 n] &@ (n - 1) - 1, 2 n], {n, 0, 8}] // Flatten (* Michael De Vlieger, Oct 12 2016 *)

Crossrefs

Cf. A002378, A002522 (position of evens in a(n)).

Sequence in context: A048212 A282864 A277518 * A353730 A077159 A277677

Adjacent sequences: A277380 A277381 A277382 * A277384 A277385 A277386

Keyword

nonn,base

Author

Eric Angelini and Jean-Marc Falcoz, Oct 12 2016

Status

approved