|
Search: id:A062325
|
|
|
| A062325 |
|
n for which phi(prime(n)) is a perfect square. |
|
+0
6
|
|
| 1, 3, 7, 12, 26, 45, 55, 79, 106, 123, 211, 252, 422, 446, 595, 723, 907, 1019, 1101, 1448, 1595, 1687, 1797, 1849, 1949, 2058, 2393, 2516, 2703, 2819, 3146, 3339, 3477, 3626, 4353, 4437, 4590, 5153, 5398, 5653, 5836, 6276, 6543, 6736, 6911, 7207, 7695
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Also A002496 indexed by A000040.
|
|
LINKS
|
Harry J. Smith, Table of n, a(n) for n=1,...,1000
|
|
FORMULA
|
A062325(n) = A000720[A002496(n)] A000040[A062325(n)] = A002496(n) Sqrt[A062325(n)-1] = A005574(n)
|
|
EXAMPLE
|
a(8)=79 because the 79th prime is 401 and phi(401) is 400 = 20^2. a(15)=595 because the 595th prime is 4357 and phi(4357) is 4356 = 66^2.
|
|
MATHEMATICA
|
Flatten[Position[Table[IntegerQ[Sqrt[Prime[w]-1]], {w, 1, 25000}], True]]
|
|
PROGRAM
|
(PARI) for(n=1, 1600, if(issquare(eulerphi(prime(n))), print(n)))
(PARI) { default(primelimit, 2*10^8); n=m=0; forprime (p=2, 2*10^8, m++; if (issquare(eulerphi(p)), write("b062325.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 05 2009]
|
|
CROSSREFS
|
Cf. A000040, A000720, A001912, A002496, A005574, A062325, A090693.
Sequence in context: A029452 A034434 A167491 this_sequence A099811 A063072 A007626
Adjacent sequences: A062322 A062323 A062324 this_sequence A062326 A062327 A062328
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Jason Earls (zevi_35711(AT)yahoo.com), Jul 05 2001
|
|
EXTENSIONS
|
More terms from Labos E. (labos(AT)ana.sote.hu), Jul 09 2001
|
|
|
Search completed in 0.002 seconds
|
