|
| |
|
|
A163666
|
|
Numbers n such that n=prime(sigma(phi(pi(n)))).
|
|
1
| |
|
|
2, 5, 47, 107, 1613, 5653, 21557, 230047, 821603, 8145173, 47073007, 68939141, 76040521, 196388147, 240595631, 433046543, 1085166671, 2269551127, 4670405591, 9784786813, 104484802043, 420065905307, 474962067289, 2616252796471, 5804170333301
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| It is obvious that all terms are primes.
|
|
|
FORMULA
| a(n) = A000040(A018784(n))
|
|
|
MATHEMATICA
| Do[If[n=Prime[m]; m==DivisorSigma[1, EulerPhi[PrimePi[n]]], Print[n]], {m, 235000000}]
|
|
|
CROSSREFS
| Cf. A000010, A000040, A000720, A000203, A163665.
Sequence in context: A023273 A041729 A078665 * A093552 A112266 A060808
Adjacent sequences: A163663 A163664 A163665 * A163667 A163668 A163669
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 04 2009
|
|
|
EXTENSIONS
| Formula and six more terms from Max Alekseyev (maxale(AT)gmail.com), Jun 25 2011
|
| |
|
|
