Respuesta :

ehylt

Answer:

I don't know but

1+2=3

3+3=6

6+4=10

10+5=15

if this helps you make any sense of it.. tell me

Step-by-step explanation:

Answer:

These are triangular numbers.

Step-by-step explanation:

The explicit formula for the nth term of the sequence id 1/2n(n+1).

So for, example, the 6th term =  1/2*6(6+1)

= 21.

They all fit exactly into equilateral triangles.