A356340 - cp's OEIS frontend

A356340 a(n) = Sum_{k=1..n} binomial(2n, n-k) phi(k), where phi is the Euler totient function.

n	a(n)
1	1
2	5
3	23
4	102
5	444
6	1909
7	8133
8	34404
9	144714
10	605920
11	2527348
12	10507978
13	43569096
14	180219699
15	743907057
16	3065019864
17	12607648238
18	51783970314
19	212412697368
20	870249992168
21	3561502879100
22	14560944187796
23	59476980459794
24	242741090637012
25	989921853052930
26	4034101567907172

[1, 5, 23, 102, 444, 1909, 8133, 34404, 144714, 605920, 2527348, 10507978, 43569096, 180219699, 743907057, 3065019864, 12607648238, 51783970314, 212412697368, 870249992168, 3561502879100, 14560944187796, 59476980459794, 242741090637012, 989921853052930, 4034101567907172]

cp's OEIS Frontend

A356340 a(n) = Sum_{k=1..n} binomial(2n, n-k) phi(k), where phi is the Euler totient function.

Table of values

List of values

cp's OEIS Frontend

A356340 a(n) = Sum_{k=1..n} binomial(2*n, n-k) * phi(k), where phi is the Euler totient function.

Table of values

List of values

A356340 a(n) = Sum_{k=1..n} binomial(2n, n-k) phi(k), where phi is the Euler totient function.