Sequences and series: convergence
Claire Celia, A T F Nice, K F Elliott · 1985
A sequence u0, u1, u2, …, un, … is a succession of expressions, each formed uniquely by some given procedure, e.g. 11, 22, 33, …, r r , … is a sequence defined by u r = r r . 2,2,4,6,10,…, u r ,… $$2,2,4,6,10, \ldots ,{u_r}, \ldots $$ is a sequence defined by u1 = u2 = 2, u r = ur-1 + ur-2, when r > 2.