A277377 Each odd integer k is followed by k even integers.

1, 0, 3, 2, 4, 6, 5, 8, 10, 12, 14, 16, 7, 18, 20, 22, 24, 26, 28, 30, 9, 32, 34, 36, 38, 40, 42, 44, 46, 48, 11, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 13, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 15, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 17, 128, 130, 132

Offset

1,3

Comments

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

Sequence places odd numbers (2n - 1) at position A002061(n). First even number to appear after this is A001105(n - 1). - Michael De Vlieger, Oct 12 2016

Links

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

Formula

a(m*(m+1) + 1) = 2m + 1 for m > 0. - David A. Corneth, Oct 11 2016

Example

As a(1) = 1, we take for a(2) the even integer "0"; we then extend the sequence with a(3) which must be the smallest odd integer not yet present: this is "3"; we take for a(4), a(5) and a(6) the 3 smallest even integers not yet present: they are 2, 4 and 6; we then extend the sequence with the smallest odd available integer, which is a(7) = 5. Etc.

Mathematica

Table[Prepend[2 Range[#^2, #^2 + 2 n - 2] &@ (n - 1), 2 n - 1], {n, 9}] // Flatten (* Michael De Vlieger, Oct 12 2016 *)

Crossrefs

Cf. A001105, A002061 (Position of odd numbers in a(n)).

Sequence in context: A254108 A093573 A126290 * A227741 A059417 A078824

Adjacent sequences: A277374 A277375 A277376 * A277378 A277379 A277380

Keyword

nonn,base

Author

Eric Angelini and Jean-Marc Falcoz, Oct 11 2016

Status

approved