A071632 Number of terms in the set InvPhi(1024*prime(n)), where prime(n) is the n-th prime.

13, 43, 31, 24, 32, 16, 13, 8, 14, 27, 4, 24, 11, 16, 0, 18, 7, 8, 16, 19, 16, 12, 18, 19, 18, 12, 0, 14, 6, 18, 10, 23, 9, 10, 17, 8, 4, 28, 5, 11, 20, 12, 18, 22, 0, 10, 0, 6, 0, 6, 21, 32, 0, 11, 4, 0, 16, 8, 20, 19, 0, 18, 14, 3, 10, 5, 12, 16, 14, 2, 0, 26, 0, 16, 0, 0, 0, 14, 14

Offset: 1

Author

Labos Elemer, May 30 2002

Keywords

• nonn

Examples

			InvPhi(1024*31) = {39685,63496,79370,95244}, so a(11) = 4.
Observe that a(15) = 0 because 47 needs a very large 2^i multiplier (instead of 1024) to give a nonempty InvPhi set.
		

Links

• Donovan Johnson, Table of n, a(n) for n = 1..1000
• Max Alekseyev, PARI/GP Scripts for Miscellaneous Math Problems (invphi.gp).

Crossrefs

Cf. A000010, A002202, A005277, A007617, A058888, A071629, A071630, A071631, A071633, A071634.

Programs

Maple

[seq(nops(invphi(1024*ithprime(i))),i=1..128)];

PARI

a(n) = invphiNum(1024 * prime(n)); \\ Amiram Eldar, Nov 11 2024, using Max Alekseyev's invphi.gp