Sequence with variable pattern

Nov 2018
24
1
Iran
Hello. I've got the sequence below and I wonder if it has a public formula or not.
1 , 2 , 4 , 7 , 11 , ....
The pattern is actually growing by one each step.
1 +1 =2
2+2 = 4
4+3=7
7+4=11
11+5=16
.
.
.
I didn't know which thread to post it by the way . thank you.
 
Dec 2015
1,084
169
Earth
\(\displaystyle \dfrac{n^2 - n}{2} +1\).
 
Nov 2018
24
1
Iran
Great.And could you give hints on how'd you get that?
thanks
 
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