Usually when a person is making stuff in Dynamo, they aren’t making just one or 2 things.  More often than not, you are actually making a ton of stuff, series or related ranges of items.  This can require inputting lists of numbers to position and arrange your stuff.

Some standard nodes exist for this, namely Number Range and Number Sequence

But you can also insert ranges and sequences directly into certain nodes following this syntax

0..4 will yield  0,1,2,3,4

0..4..2 will yield 0,2,4

0..1..#5 will yield 0, 0.25, 0.5, 0.75, 1

Start..#List Length..Interval
0..#4..10 will yield 0,10,20,30

Additionally, you can insert variables within the ranges and sequences like 0..#a..50