[b]Zwillinge[/b]: Zwei Tripel (a,b,c) und (k,m,n), deren Summen und deren Kehrwertsummen gleich sind.[br]z.B. ( 5,6,20) und (4,9,18), 5+6+20 = 4+9+18 = 31, 1/5+1/6+1/20 = 1/4+1/9+1/18 = 5/12[br][b]Drillinge[/b]: [br]Folgende drei Versionen sind:[br]a) 17 + 34 + 85 = 16 + 40 + 80 = 15 + 55 + 66 = 136[br] 1/17+1/34+1/85 = 1/16+1/40+1/80 = 1/15+1/55+1/66 = 1/10[br]b) 22 + 33 + 132 = 18 + 52 + 117 = 17 + 68 + 102 = 187[br] 1/22+1/33+1/132 = 1/18+1/52+1/117 = 1/17+1/68+1/102 = 1/12[br]c) 44 + 55 + 110 = 40 + 65 + 104 = 38 + 76 + 95 = 209[br] 1/44+1/55+1/110 = 1/40+1/65+1/104 = 1/38+1/76+1/95 = 1/20