From ixl.com, where "All of IXL's dynamic math and language arts skills are aligned to your standards, including:
The Common Core State Standards
All 50 states and D.C."
Accessed from ixl's high school math page, here are three problems from the "Find terms of a sequence (Precalculus - U.1)" page:
The arithmetic series problem set in Wentworth's New School Algebra:
ixl bases its pre-calculus sequence problems on this standard from the Core Standards for High School:
High School: Functions » Interpreting Functions » Understand the concept of a function and use function notation. » 3
Recognize that sequences are functions, sometimes defined recursively, whose domain is a subset of the integers. For example, the Fibonacci sequence is defined recursively by f(0) = f(1) = 1, f(n+1) = f(n) + f(n-1) for n ≥ 1.
Arguably, ixl's problems meet the above standard: arguably, doing ixl's problems encourages students to have the various recognitions that the standard specifies. Recognizing "that sequences are functions," etc., doesn't necessarily involve finding particular functions for particular sequences, or, for that matter, actually doing anything with sequences. Recognizing, after all, is not the same as doing.
So, in choosing words like "recognize" and "understand," have the Common Core authors chosen their words wisely?