A341779 -id:A341779 - cp's OEIS frontend

A341780 Starts of runs of 3 consecutive anti-tau numbers (A046642).

3, 15, 195, 255, 483, 783, 1023, 1155, 1295, 1443, 1599, 2703, 3363, 4623, 4899, 5183, 6399, 6723, 7395, 7743, 8463, 8835, 10815, 11235, 11663, 12099, 12543, 15375, 16383, 16899, 17955, 18495, 20163, 24963, 25599, 26895, 27555, 31683, 33855, 35343, 36099, 37635

Offset: 1

Graph
List
Refs
Listen
History
Text
Internal format

Amiram Eldar, Feb 19 2021

nonn

Since the even anti-tau numbers (A268066) are square numbers, all the terms are of the form 4*k^2 - 1, and there cannot be a run of more than 3 consecutive anti-tau numbers.

			3 is a term since 3, 4 and 5 are all anti-tau numbers: gcd(3, tau(3)) = gcd(3, 2) = 1, gcd(4, tau(4)) = gcd(4, 3) = 1 and gcd(5, tau(5)) = gcd(5, 2) = 1.

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

Subsequence of A000466, A046642 and A341779.

Cf. A000010, A009191, A268066.

antiTauQ[n_] := CoprimeQ[n, DivisorSigma[0, n]]; Select[4*Range[100]^2 - 1, AllTrue[# + {0, 1, 2}, antiTauQ] &]

cp's OEIS Frontend

A341780 Starts of runs of 3 consecutive anti-tau numbers (A046642).

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Mathematica