A384073 Numbers k such that d(k)^d(k) == d(k) (mod k), where d = A000005.

4, 6, 14, 16, 21, 36, 50, 56, 75, 120, 132, 162, 168, 210, 264, 276, 280, 312, 330, 390, 405, 440, 462, 520, 546, 616, 726, 728, 744, 770, 784, 858, 910, 930, 984, 1012, 1016, 1144, 1155, 1230, 1240, 1260, 1302, 1365, 1430, 1464, 1640, 1722, 1736, 1778, 1830

Offset

1,1

Links

Table of n, a(n) for n=1..51.

Example

4 is a term because 3^3 = 3 (mod 4), where 3 is the number of divisors of 4.

Mathematica

Select[Range[1450], Mod[(tau=DivisorSigma[0, #])^tau, #]==tau &] (* Stefano Spezia, May 18 2025 *)

Prog

(Magma) [k: k in [1..1500] | #Divisors(k)^#Divisors(k) mod k eq #Divisors(k)];

Crossrefs

Cf. A000005.

Sequence in context: A310619 A343501 A029641 * A089377 A310620 A310621

Adjacent sequences: A384070 A384071 A384072 * A384074 A384075 A384076

Keyword

nonn

Author

Juri-Stepan Gerasimov, May 18 2025

Status

approved