A181388 - cp's OEIS frontend

A181388 a(n) = Sum_{k=1..n} 2^T(k-1), where T = A000217 are the triangular numbers 0, 1, 3, 6, 10, ... . For n=0 we have the empty sum equal to 0.

n	a(n)
0	0
1	1
2	3
3	11
4	75
5	1099
6	33867
7	2131019
8	270566475
9	68990043211
10	35253362132043
11	36064050381096011
12	73823040345219302475
13	302305277944002512979019
14	2476182383848704552311227467
15	40567295389687189552446813799499
16	1329268563080305560093359507094144075

[0, 1, 3, 11, 75, 1099, 33867, 2131019, 270566475, 68990043211, 35253362132043, 36064050381096011, 73823040345219302475, 302305277944002512979019, 2476182383848704552311227467, 40567295389687189552446813799499, 1329268563080305560093359507094144075]

cp's OEIS Frontend

A181388 a(n) = Sum_{k=1..n} 2^T(k-1), where T = A000217 are the triangular numbers 0, 1, 3, 6, 10, ... . For n=0 we have the empty sum equal to 0.

Table of values

List of values