A081494 - cp's OEIS frontend

A081494 Start with Pascal's triangle; form a triangle by sliding down n steps from top on both sides and including the horizontal row, deleting the inner numbers; a(n) = sum of entries on perimeter of triangle.

n	a(n)
1	1
2	3
3	7
4	13
5	23
6	41
7	75
8	141
9	271
10	529
11	1043
12	2069
13	4119
14	8217
15	16411
16	32797
17	65567
18	131105
19	262179
20	524325
21	1048615
22	2097193
23	4194347
24	8388653
25	16777263
26	33554481
27	67108915
28	134217781
29	268435511
30	536870969
31	1073741883
32	2147483709

[1, 3, 7, 13, 23, 41, 75, 141, 271, 529, 1043, 2069, 4119, 8217, 16411, 32797, 65567, 131105, 262179, 524325, 1048615, 2097193, 4194347, 8388653, 16777263, 33554481, 67108915, 134217781, 268435511, 536870969, 1073741883, 2147483709]

cp's OEIS Frontend

A081494 Start with Pascal's triangle; form a triangle by sliding down n steps from top on both sides and including the horizontal row, deleting the inner numbers; a(n) = sum of entries on perimeter of triangle.

Table of values

List of values