define own color pallettee (replicatd R color pallette example)

You can get hexadecimal code for terrain.colors by typing the following in R:

> terrain.colors(6)
> t(col2rgb(terrain.colors(6)))
     red green blue
[1,]   0   166    0
[2,]  99   198    0
[3,] 230   230    0
[4,] 234   182   78
[5,] 238   185  159
[6,] 242   242  242

You can pick the color from different sources, even from nature or based on your own choice !

Formula:

For R column and row 2:
=HEX2DEC(LEFT(A2,2))

For G column and row 2:
=HEX2DEC(MID(A2, 3,2))

For B column and row 2:
=HEX2DEC(MID(A2, 5,2))

You can add color one by one, up to 6.

Plot in R:
barplot(seq(1:6), col=terrain.colors(6))

More color to practice:
> heat.colors(6)
[1] "#FF0000FF" "#FF4000FF" "#FF8000FF" "#FFBF00FF" "#FFFF00FF" "#FFFF80FF"
> t(col2rgb(heat.colors(6)))
     red green blue
[1,] 255     0    0
[2,] 255    64    0
[3,] 255   128    0
[4,] 255   191    0
[5,] 255   255    0
[6,] 255   255  128

> t(col2rgb(topo.colors(6)))
     red green blue
[1,]  76     0  255
[2,]   0   229  255
[3,]   0   255   77
[4,] 230   255    0
[5,] 255   255    0
[6,] 255   224  179
> t(col2rgb(cm.colors(6)))
     red green blue
[1,] 128   255  255
[2,] 170   255  255
[3,] 213   255  255
[4,] 255   213  255
[5,] 255   170  255
[6,] 255   128  255

> t(col2rgb(rainbow(6)))
     red green blue
[1,] 255     0    0
[2,] 255   255    0
[3,]   0   255    0
[4,]   0   255  255
[5,]   0     0  255
[6,] 255     0  255

More list of favorate colors:

		R	G	B
aquamarine4	#458B74	69	139	116
darkolivegreen	#556B2F	85	107	47
darkolivegreen4	#6E8B3D	110	139	61
darkgreen	#006400	0	100	0
darkorchid4	#68228B	104	34	139
cadetblue	#5F9EA0	95	158	160
cadetblue4	#53868B	83	134	139
burlywood4	#8B7355	139	115	85
chartreuse4	#458B00	69	139	0
aliceblue	#F0F8FF	240	248	255
deepskyblue4	#00688B	0	104	139
forestgreen	#228B22	34	139	34
khaki4	#8B864E	139	134	78
lightcoral	#F08080	240	128	128
mediumaquamarine	#66CDAA	102	205	170
lightgreen	#90EE90	144	238	144
mediumorchid4	#7A378B	122	55	139
midnightblue	#191970	25	25	112
lightseagreen	#20B2AA	32	178	170
lightsalmon4	#8B5742	139	87	66
steelblue4	#36648B	54	100	139
tan4	#8B5A2B	139	90	43
yellowgreen	#9ACD32	154	205	50
slategrey	#708090	112	128	144

Due to presence of # and 6 digit code, the formula for R, G, B calculated is slightly modified.

For R:

=HEX2DEC(MID(C2,2,2))

For G:
=HEX2DEC(MID(C2, 4,2))

For R:
=HEX2DEC(MID(C2, 6,2))