| 12345678910111213141516 |
- # Added
- # https://oeis.org/A000203
- # 1, 3, 4, 7, 6, 12, 8, 15, 13, 18, 12, 28, 14, 24, 24, 31, 18, 39, 20, 42, 32, 36, 24, 60, 31, 42, 40, 56, 30, 72, 32, 63, 48, 54, 48, 91, 38, 60, 56, 90, 42, 96, 44, 84, 78, 72, 48, 124, 57, 93, 72, 98, 54, 120, 72, 120, 80, 90
- a(n) = Sum_{k=1..n} gcd(n, k) / phi(n / gcd(n, k)), where phi(k) is the Euler totient function. - ~~~~
- func foo(n) {
- sum(1..n, {|k|
- gcd(n, k) / euler_phi(n / gcd(n, k))
- })
- }
- say 50.of(foo)
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