a(n) is the index of the smallest triangular number containing exactly n 2's.
A048357
a(n) is the index of the smallest triangular number containing exactly n 2's.
Terms
- a(0) =6a(1) =49a(2) =215a(3) =651a(4) =6651a(5) =66367a(6) =206020a(7) =635959a(8) =6651759a(9) =21411348a(10) =66651759a(11) =666816649a(12) =666651759a(13) =6666651759a(14) =64687340681a(15) =210818509825
External references
- oeis: A048357