|
Search: id:A112011
|
|
|
| A112011 |
|
Numbers n with even length such that phi(n)=phi(d_1^d_2)*phi(d_3^d_4) *...*phi(d_(k-1)^d_k) where d_1 d_2 ... d_k is the decimal expansion of n. |
|
+0
4
|
|
| 24, 1064, 2592, 6520, 9234, 145166, 245344, 296480, 372780, 491520, 531765, 546410, 566250, 664062, 12806910, 12826710, 14466530, 15408692, 15621268, 17473715, 19946352, 22297520, 23256720, 30537364, 30869280, 32118177
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
For the third term we have the relation 2592=2^5*9^2. So phi(2592)=phi(2^5*9^2)=phi(2^5)*phi(9^2).
|
|
EXAMPLE
|
39602752 is in the sequence because phi(39602752)=
phi(3^9)*phi(6^0)*phi(2^7)*phi(5^2).
|
|
MATHEMATICA
|
Do[h = IntegerDigits[n]; k = Length[h]; If[EvenQ[k] && Select[ Range[k/2], h[[2#-1]] == 0 &] == {} && EulerPhi[n]== Product[EulerPhi[h[[2j-1]]^h[[2j]]], {j, k/2}], Print[n]], {n, 35000000}]
|
|
CROSSREFS
|
Cf. A110084, A112009, A112010.
Sequence in context: A006175 A058810 A129622 this_sequence A112010 A046906 A130552
Adjacent sequences: A112008 A112009 A112010 this_sequence A112012 A112013 A112014
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
Farideh Firoozbakht (mymontain(AT)yahoo.com), Aug 26 2005
|
|
|
Search completed in 0.002 seconds
|
