Kenneth H. Rosen, Discrete Mathematics and Its Applications (8th Edition).

• Comprehensive introduction to sequences, recurrence relations, and their applications.

Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein, Introduction to Algorithms (3rd Edition).

• Standard algorithms for finding increasing and decreasing subsequences.

Wikipedia: Sequence

• https://en.wikipedia.org/wiki/Sequence
• Theory, types, and examples of sequences.

Wikipedia: Longest Increasing Subsequence

• https://en.wikipedia.org/wiki/Longest_increasing_subsequence
• Algorithms and applications for increasing subsequences.

NPTEL: Discrete Mathematics

• https://nptel.ac.in/courses/111/106/111106086/
• Video lectures and notes on sequences and recurrence relations.