3
Two solutions. With Binet's formula \documentclass{article} \usepackage[paperwidth=3cm,paperheight=4cm,textheight=2cm]{geometry} \usepackage{xparse} \ExplSyntaxOn \fp_const:Nn \c_rudstep_phi_fp { (sqrt(5)+1)/2 } % the golden ratio \DeclareExpandableDocumentCommand{\fibonacci}{m} { \fp_eval...