A349235 Numbers k such that k and k+4 are consecutive cubefree numbers.

1374, 4373, 4911, 5749, 6857, 13309, 13374, 16118, 21247, 24351, 25622, 28374, 31373, 32749, 33613, 40471, 41741, 48247, 49623, 49733, 52622, 55374, 57966, 58373, 59749, 75247, 76623, 79622, 82374, 85373, 86749, 90206, 94470, 98439, 102247, 103623, 106622, 107701

Offset

1,1

Comments

The asymptotic density of this sequence is 0.000379098586237504... (Mossinghoff et al., 2021).

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Michael J. Mossinghoff, Tomás Oliveira e Silva, and Tim Trudgian, The distribution of k-free numbers, Mathematics of Computation, Vol. 90, No. 328 (2021), pp. 907-929; arXiv preprint, arXiv:1912.04972 [math.NT], 2019-2020.

Example

1374 is a term since 1374 = 2*3*229 and 1374 + 4 = 1378 = 2*13*53 are cubefree, and 1374 + 1 = 1375 = 5^3*11, 1374 + 2 = 1376 = 2^5*43 and 1374 + 3 = 1377 = 3^4*17 are not.

Mathematica

cubeFreeQ[n_] := AllTrue[FactorInteger[n][[;; , 2]], # < 3 &]; Select[Range[10^5], Boole[cubeFreeQ /@ (# + Range[0, 4])] == {1, 0, 0, 0, 1} &]

Crossrefs

Cf. A004709, A046099, A340152, A349233, A349234.

Sequence in context: A069490 A239974 A258964 * A045131 A365868 A056049

Adjacent sequences: A349232 A349233 A349234 * A349236 A349237 A349238

Keyword

nonn

Author

Amiram Eldar, Nov 11 2021

Status

approved