A003555 - cp's OEIS frontend

A003555 Sum_{i=1..(10^n - 1)/9} i, or ((10^n -1)/9)*((10^n -1)/9 +1)/2 (n-th term is the middle 2(n-1) digits of the (n+9)-th term for n > 1).

n	a(n)
1	1
2	66
3	6216
4	617716
5	61732716
6	6172882716
7	617284382716
8	61728399382716
9	6172839549382716
10	617283951049382716
11	61728395066049382716
12	6172839506216049382716
13	617283950617716049382716
14	61728395061732716049382716
15	6172839506172882716049382716

[1, 66, 6216, 617716, 61732716, 6172882716, 617284382716, 61728399382716, 6172839549382716, 617283951049382716, 61728395066049382716, 6172839506216049382716, 617283950617716049382716, 61728395061732716049382716, 6172839506172882716049382716]

cp's OEIS Frontend

A003555 Sum_{i=1..(10^n - 1)/9} i, or ((10^n -1)/9)*((10^n -1)/9 +1)/2 (n-th term is the middle 2(n-1) digits of the (n+9)-th term for n > 1).

Table of values

List of values