Smallest triangular number k such that k-1 has exactly n (not necessarily distinct) prime factors.

A081950

Smallest triangular number k such that k-1 has exactly n (not necessarily distinct) prime factors.

Terms

    a(0) =3a(1) =10a(2) =21a(3) =55a(4) =253a(5) =325a(6) =1081a(7) =4753a(8) =8001a(9) =18145a(10) =226801a(11) =293761a(12) =7378561a(13) =1181953a(14) =33566721a(15) =184291201a(16) =471905281a(17) =75479041a(18) =924908545a(19) =4831985665a(20) =8590131201a(21) =137438167041a(22) =146163916801a(24) =309236465665

External references