Less frequent are litters of quadruplet, quintuplet, and even sextuplet kids. The Genain quadruplets (born in 1930) are a set of identical quadruplet sisters. A vierling (German for "quadruplet") has four barrels. Four quadruplet (or quartole) eighth notes would also equal a dotted quarter note. The solution to the iso-Gregorian quadruplet is a Diophantine problem. Each training rating is a quadruplet of the form codice 1. A prime quadruplet of this form is also called a prime decade. The inferior and superior colliculi are known collectively as the corpora quadrigemina (Latin, "quadruplet bodies"). Quadruplet births are becoming increasingly common due to fertility treatments. For example, 4-3-18, 1980-3-18, and 3964-3-18 share the same four-pillar quadruplet. In September 2010 Ken Davis announced a 1,004-digit quadruplet with "p" = 2 + 1582534968299. When four photos or paints are together, it is called photography quadruplet.