a(n) is the index of the smallest tetrahedral number with exactly n prime factors (counted with multiplicity), or -1 if no such number exists.

A359090

a(n) is the index of the smallest tetrahedral number with exactly n prime factors (counted with multiplicity), or -1 if no such number exists.

Terms

    a(0) =1a(1) =-1a(2) =2a(3) =4a(4) =6a(5) =8a(6) =14a(7) =30a(8) =48a(9) =62a(10) =126a(11) =160a(12) =350a(13) =510a(14) =1022a(15) =2046a(16) =1024a(17) =4095a(18) =4094a(19) =13310a(20) =28672a(21) =32768a(22) =65534a(23) =180224a(24) =262142a(25) =360448a(26) =262143a(27) =2097151a(28) =3276800a(29) =4194302

External references