A341811 a(n) = 1/(Sum_{k=1..n} 1/phi(A341810(n)*k)).

1, 1, 1, 2, 4, 8, 3, 24, 12, 3, 120, 30, 9, 45, 32, 120, 320, 160, 720, 2880, 256, 1280, 15840, 1408, 704, 2112, 3168, 9504, 88704, 199584, 221760, 133056, 8316, 22176, 22176, 76032, 57024, 19008, 1540, 19008, 23100, 138600, 55440, 3465, 14784, 64064, 239085

Offset

1,4

Links

Seiichi Manyama, Table of n, a(n) for n = 1..55

Example

a(2) = 1/(1/phi(3)+1/phi(6)) = 1/(1/2+1/2) = 1.
a(3) = 1/(1/phi(4)+1/phi(8)+1/phi(12)) = 1/(1/2+1/4+1/4) = 1.
a(4) = 1/(1/phi(7)+1/phi(14)+1/phi(21)+1/phi(28)) = 1/(1/6+1/6+1/12+1/12) = 2.

Prog

(PARI) a(n) = my(k=1); while (denominator(m=1/sum(j=1, n, 1/eulerphi(k*j))) != 1, k++); m;

Crossrefs

Cf. A000010, A341810, A341814.

Sequence in context: A352782 A289271 A354169 * A332306 A223699 A231610

Adjacent sequences: A341808 A341809 A341810 * A341812 A341813 A341814

Keyword

nonn

Author

Seiichi Manyama, Feb 20 2021

Status

approved