A299205 Numbers k such that k-1 divides tau(k), where tau(k) = A000594(k) is Ramanujan's tau function.

2, 3, 10, 14, 15, 56, 57, 59, 70, 85, 105, 107, 116, 136, 209, 267, 295, 323, 352, 393, 415, 442, 530, 551, 645, 646, 760, 855, 1197, 1288, 1342, 1415, 1472, 1496, 1625, 1765, 1953, 2002, 2255, 2485, 2847, 2945, 3039, 3382, 3591, 3745, 3905, 4233, 4264, 4313

Offset: 1

Author

Seiichi Manyama, Feb 05 2018

Keywords

• nonn

Comments

Numbers k such that A299204(k) = 0.

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..500
• Eric Weisstein's World of Mathematics, Tau Function.

Crossrefs

For the sequence when n is prime see A299172.

Cf. A000594, A063938, A299157, A299204.

Programs

Mathematica

Select[Range[2, 5000], Divisible[RamanujanTau[#], #-1] &] (* Amiram Eldar, Jan 10 2025 *)

PARI

isok(n) = (ramanujantau(n) % (n-1)) == 0; \\ Michel Marcus, Feb 05 2018