It makes all the sense in the world, and if you’re playing with that at thirteen, I take my hat off
If you want to check your result, you can work in reverse by finding a succinct expression for the sum of all natural numbers n from 0 to N, both included (though it’s not like it matters if you exclude 0 ), and then using that to compute your sum of 2 n + 1. It’s what Gauss did, as the legend has it, when his teacher tried to keep the class busy for a while by making them add up 1 + 2 + ⋯ + 100.
_________________
The red lake has been forgotten. A dust devil stuns you long enough to shroud forever those last shards of wisdom. The breeze rocking this forlorn wasteland whispers in your ears, “Não resta mais que uma sombra”.