Question 1163967
from -1 to 3 is 4 
to 22 is 19.  the difference between 4 and 19 is 15. 
then 39. next difference is 20. difference between 15 and 20 is 5. And all the others have difference 5
then 64. next difference is 25
then 94 next difference is 30
then 129 next difference is 35
then 169  (next difference is 40) and the term is 517

-1----
3----+4----
22---19---15----
61---39---20---5
125--64---25---5
219--94---30---5
348--129--35--5
517--169--40---5