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A277377 Each odd integer k is followed by k even integers. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 25 14:21 EST 2020. Contains 338624 sequences. (Running on oeis4.)