Package - ggthemes
Novelty - No
Type - sequential

ggthemes - excel_Grayscale

Github

jrnold/ggthemes

CRAN

ggthemes

Use with paletteer package:

library(paletteer)
paletteer_d("ggthemes::excel_Grayscale")

Use raw:

c("#DDDDDDFF", "#B2B2B2FF", "#969696FF", "#808080FF", "#5F5F5FFF", "#4D4D4DFF")