Sequins and sequence are easily confused words.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It suggests what word you may want to save time, but quite often, its suggestions couldn’t be more off base and produces humorous results.
Sequin is a noun, its plural form is sequins. Sequins are round, shiny plastic discs used to enhance the decoration on evening dresses, or costumes of partygoers, dancers, and ice skaters’ costumes. When light hits sequins, they sparkle like a fish’s scales.
Most small sequins have a hole in the center so they can be sewed to the surface of fabric with clear thread. Sequins come in all sizes, and sometimes they need to move a little. On a textured or fringed garment, all those sparkles need to move around, like Latin ballroom dance competitors. So larger sequins that often have a hole closer to one edge (instead of the center) are also called paillettes.
Sequence is a noun. It means an orderly line or set of things, like numbers.
The following sentence uses both words correctly:
Sequoia spent months sewing thousands of sequins in sequence on her spandex tube dress to get the perfect mermaid costume ready for the Halloween Ball.