A039786 phi(a(n)) is equal to the multiplicative projection of (a(n)-1).

2, 3, 5, 7, 9, 11, 13, 23, 29, 31, 43, 47, 53, 59, 61, 67, 71, 79, 83, 103, 107, 131, 139, 149, 157, 167, 173, 179, 191, 211, 223, 227, 229, 239, 263, 269, 277, 283, 293, 311, 317, 331, 347, 349, 359, 367, 373, 383, 389, 419, 421, 431, 439, 443, 461, 463, 467, 479

Offset

1,1

Comments

Only primes (except 9) may qualify.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

phi(29)=28, 28=2^2*7^1, 2*2*7*1=28.

Prog

(PARI) is(n)=my(f=factor(n)); eulerphi(f)==prod(i=1, #f~, f[i, 1]*f[i, 2])-1 \\ Charles R Greathouse IV, Mar 11 2014

Crossrefs

Cf. A000010, A000026.

Sequence in context: A189710 A024678 A265384 * A102422 A062427 A127721

Adjacent sequences: A039783 A039784 A039785 * A039787 A039788 A039789

Keyword

nonn

Author

Olivier Gérard

Extensions

a(1) inserted by Charles R Greathouse IV, Mar 11 2014

Status

approved