a(n) is the index of the smallest triangular number containing exactly n 7's.
A048362
a(n) is the index of the smallest triangular number containing exactly n 7's.
Terms
- a(0) =12a(1) =59a(2) =381a(3) =3684a(4) =8692a(5) =70381a(6) =122292a(7) =3762381a(8) =7453707a(9) =18856074a(10) =124721736a(11) =587838545a(12) =3996943276a(13) =18845571218a(14) =27483805332a(15) =394393554074
External references
- oeis: A048362