A292742 Odd numbers k such that 2^psi(k) == phi(k) (mod k).

1, 5, 10393, 45411263, 31761301667, 70697569679

Offset

1,2

Comments

a(7) > 5*10^11. - Giovanni Resta, Sep 23 2017

Links

Table of n, a(n) for n=1..6.

Example

10393 = 19*547 is a term because 2^((19 + 1)*(547 + 1)) == (19 - 1)*(547 - 1) (mod 19*547).

Prog

(PARI) a001615(n) = my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1));
isok(n) = n%2==1 && Mod(2, n)^a001615(n)==eulerphi(n); \\ after Charles R Greathouse IV at A001615

Crossrefs

Cf. A000010, A001615, A292544.

Sequence in context: A212617 A160741 A101846 * A260262 A058051 A242772

Adjacent sequences: A292739 A292740 A292741 * A292743 A292744 A292745

Keyword

nonn,more

Author

Altug Alkan, Sep 22 2017

Extensions

a(5)-a(6) from Giovanni Resta, Sep 23 2017

Status

approved