|
| |
|
|
A065572
|
|
Composite n such that phi(n) = phi(n-1) + phi(n-2).
|
|
3
| |
|
|
1037, 1541, 6527, 9179, 55387, 61133, 72581, 110177, 152651, 179297, 244967, 299651, 603461, 619697, 1876727, 2841917, 3058211, 3971321, 4110653, 4316441, 4397317, 6008861
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| 619697=13*73*653 is the smallest solution not of the form p or pq for distinct primes p and q.
|
|
|
LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,50
|
|
|
MATHEMATICA
| Select[ Range[3, 10^7], !PrimeQ[ # ] && EulerPhi[ # ] == EulerPhi[ # - 1] + EulerPhi[ # - 2] & ]
|
|
|
PROG
| (PARI) { n=0; e1=eulerphi(2); e2=eulerphi(1); for (m=3, 10^9, e=eulerphi(m); if (!isprime(m) && e==e2 + e1, write("b065572.txt", n++, " ", m); if (n==100, return)); e2=e1; e1=e ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 23 2009]
|
|
|
CROSSREFS
| Cf. A065557 (includes prime solutions)
Sequence in context: A184210 A163559 A159052 * A074673 A020395 A069456
Adjacent sequences: A065569 A065570 A065571 * A065573 A065574 A065575
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Len Smiley (smiley(AT)math.uaa.alaska.edu) and Robert G. Wilson v (rgwv(AT)rgwv.com), Nov 30 2001
|
| |
|
|
