861. 5, –1, 4, 3, 7
The nth term is the sum of the two previous terms.
862. 1, 1, 3, 5, 11
The nth term is the sum of the previous term plus twice the one before that.
863. 2, 3, –1, 4, –5
The nth term is the difference between the two previous terms.
864. 0, 2, –4, 16, –48
The nth term is 4 times the term two previous minus twice the term directly before.
865. 1, 4, 3, 8, 15
The nth term is the sum of the three previous terms.
866. 21, 34, 55, 89
The nth term is the sum of the two previous terms. This is the famous Fibonacci sequence.
867. 
868. 
869. ...
