|
Search: id:A131195
|
|
|
| A131195 |
|
Nonprime record values of Euler's totient function (A000010): 1 and composite n such that phi(n) is greater than all smaller composites. |
|
+0
1
|
|
| 1, 4, 8, 9, 15, 21, 25, 35, 49, 65, 77, 85, 91, 115, 119, 121, 143, 161, 169, 187, 203, 209, 221, 247, 253, 287, 289, 319, 323, 341, 361, 391, 403, 437, 451, 473, 481, 493, 517, 527, 529, 583, 589, 611, 629, 649, 667, 689, 697, 703, 713, 731, 767, 779, 799, 817
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
Since phi(p) = p - 1, allowing prime numbers in this sequence would make it almost the same as the list of primes, A000040, except with a 1 replacing the intial 2.
|
|
EXAMPLE
|
a(3) = 8 because phi(8) = 4, which is greater than phi(4) = phi(6) = 2. (phi(5) = 4 and phi(7) = 6 are ignored because 5 and 7 are prime).
|
|
MATHEMATICA
|
htcList = {1}; i = 4; currMax = 1; searchMax = 1000; While[i < searchMax, If[Not[PrimeQ[i]] && EulerPhi[i] > currMax, htcList = {htcList, i}; currMax = EulerPhi[i]]; i++ ]; Flatten[htcList]
|
|
CROSSREFS
|
Cf. A000010, A000040.
Sequence in context: A078177 A135135 A023886 this_sequence A020217 A141066 A018196
Adjacent sequences: A131192 A131193 A131194 this_sequence A131196 A131197 A131198
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
Alonso Delarte (alonso.delarte(AT)gmail.com), Oct 20 2007
|
|
|
Search completed in 0.002 seconds
|
