A308007 Absolute values of first differences of A081145.

1, 2, 3, 4, 5, 6, 9, 7, 8, 14, 10, 11, 18, 12, 13, 24, 15, 16, 30, 17, 19, 34, 20, 21, 39, 22, 23, 43, 25, 26, 50, 27, 28, 54, 29, 31, 57, 33, 32, 35, 36, 70, 37, 38, 73, 40, 41, 78, 42, 44, 85, 45, 46, 90, 47, 48, 94, 49, 51, 97, 52, 53, 104, 55, 56, 109, 58, 59, 116, 61, 60, 62, 63

Offset

1,2

Comments

The (signed) differences themselves are in A099004, but this sequence is important enough to have its own entry.

Conjectured (see the Slater-Velez and Velez articles) to be a permutation of the positive integers.

It appears that the terms line on two lines (this is true for the first million terms): see A308016-A308020.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..5000

P. J. Slater and W. Y. Velez, Permutations of the Positive Integers with Restrictions on the Sequence of Differences, Pacific Journal of Mathematics, Vol. 71, No. 1, 1977, 193-196.

P. J. Slater and W. Y. Velez, Permutations of the Positive Integers with Restrictions on the Sequence of Differences, II, Pacific Journal of Mathematics, Vol. 82, No. 2, 1979, 527-531.

William Y. Velez, Research problems 159-160, Discrete Math., 110 (1992), pp. 301-302.

Crossrefs

Cf. A081145, A081146, A099004, A308021.

See also A308016-A308020.

Sequence in context: A141655 A174349 A099004 * A360413 A270194 A055170

Adjacent sequences: A308004 A308005 A308006 * A308008 A308009 A308010

Keyword

nonn

Author

N. J. A. Sloane, May 13 2019

Status

approved