A339049 a(n) = A000010(2*n + 1)/A053447(n), for n >= 0.

1, 2, 2, 2, 2, 2, 2, 4, 4, 2, 4, 2, 2, 2, 2, 6, 4, 4, 2, 4, 4, 6, 4, 2, 2, 8, 2, 4, 4, 2, 2, 12, 8, 2, 4, 2, 8, 4, 4, 2, 2, 2, 16, 4, 8, 12, 12, 4, 4, 4, 2, 2, 8, 2, 6, 4, 8, 4, 12, 8, 2, 8, 2, 18, 12, 2, 12, 4, 4, 2, 4, 4, 8, 4, 2, 10, 8, 12, 6

Offset: 0

Author

Wolfdieter Lang, Dec 13 2020

Keywords

• nonn
• easy

Comments

This gives the number of seeds S(2*n+1) = a(n) needed for the complete quadrupling system modulo 2*n + 1 given in A339046.

Crossrefs

Cf. A000010, A053447, A339046.

Programs

Mathematica

Array[EulerPhi[#]/MultiplicativeOrder[4, #] &[2 # + 1] &, 61, 0] (* Michael De Vlieger, Dec 13 2020 *)

PARI

a(n) = eulerphi(2*n+1)/znorder(Mod(4, 2*n+1)); \\ Michel Marcus, Dec 15 2020

Formula

a(n) = phi(2*n + 1)/A053447(n), for n >= 0, with phi = A000010.