Catalan numbers modulo 2 k . Liu, Shu-Chung, Yeh, Jean C.-C. (2010) Journal of Integer Sequences [electronic only]
Corrigendum to "An improvement on Olson's constant for ℤₚ ⊕ ℤₚ" (Acta Arith. 141 (2010), 311-319) Gautami Bhowmik, Jan-Christoph Schlage-Puchta (2011) Acta Arithmetica
Criteria for testing Wall's question Jiří Klaška (2008) Czechoslovak Mathematical Journal In this paper we find certain equivalent formulations of Wall's question and derive two interesting criteria that can be used to resolve this question for particular primes.