Noun
specker (plural speckers)
(Australia) A person who practices specking, walking around scanning the ground for gemstones; a fossicker.
For example, if one uses the classical definition of a sequence, the set of computable numbers is not closed under the basic operation of taking the supremum of a bounded sequence (for example, consider a Specker sequence ). Source: Internet
For example, the limit of a Specker sequence is an arithmetical number that is not computable. Source: Internet