A376909 Numbers k such that none of T(k-1), T(k), and T(k+1) is cubefree, with T(n)=A000217(n).

80, 160, 161, 270, 271, 351, 512, 592, 593, 624, 686, 687, 702, 703, 750, 751, 783, 944, 999, 1024, 1025, 1134, 1135, 1215, 1248, 1249, 1375, 1376, 1456, 1457, 1566, 1567, 1647, 1808, 1888, 1889, 1998, 1999, 2079, 2240, 2320, 2321, 2375, 2400, 2401, 2402, 2430, 2431

Offset

1,1

Links

Table of n, a(n) for n=1..48.

Prog

(PARI) iscubefree(n) = n<8 || vecmax(factor(n)[, 2])<3;
T(n)=n*(n+1)/2;
is_a376909(n) = !iscubefree(T(n-1)) && !iscubefree(T(n)) && !iscubefree(T(n+1))

Crossrefs

Cf. A000217, A004709, A046099, A377160.

Sequence in context: A107931 A234134 A134769 * A371150 A295593 A043332

Adjacent sequences: A376906 A376907 A376908 * A376910 A376911 A376912

Keyword

nonn

Author

Hugo Pfoertner, Oct 18 2024

Status

approved