A381400 Numbers k >= 2 such that A115588(k) != A381399(k).

64, 81, 256, 320, 405, 448, 512, 567, 625, 704, 729, 832, 891, 1024, 1053, 1088, 1216, 1280, 1377, 1472, 1539, 1600, 1792, 1856, 1863, 1875, 1984, 2240, 2349, 2368, 2401, 2511, 2560, 2624, 2752, 2816, 2835, 2997, 3008, 3072, 3136, 3321, 3328, 3392, 3483, 3520

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Mathematica

A115588[n_] := Length[Union[NestWhile[DeleteCases[Flatten[FactorInteger[#]], 1] &, {n}, AnyTrue[#, CompositeQ] &]]];
A381399[n_] := Count[Union[Flatten[FactorInteger[n]]], _?PrimeQ];
A381400Q[k_] := A115588[k] != A381399[k];
Select[Range[2, 5000], A381400Q]

Crossrefs

Cf. A115588, A381399.

Sequence in context: A374938 A057442 A141817 * A008435 A223083 A302169

Adjacent sequences: A381397 A381398 A381399 * A381401 A381402 A381403

Keyword

nonn,easy

Author

Paolo Xausa, Feb 22 2025

Status

approved