|
Search: id:A078543
|
|
|
| A078543 |
|
Balanced refactorable numbers. |
|
+0
1
|
|
| 1, 2, 12, 56, 248, 12192, 28896, 60960, 61344, 66528, 86304, 94944, 129504, 133920, 140448, 182880, 201924, 207264, 242316, 282720, 408672, 416640, 426720, 429408, 604128, 664608, 671760, 776736, 792480, 854496, 862752, 906528
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
FORMULA
|
Intersection of A033950 and A020492.
|
|
EXAMPLE
|
n=56: tau[56]=8, sigma[56]=120,phi[56]=24, q1=120/24=5 for balancedness,q2=120/8=15 for refactorability
|
|
MATHEMATICA
|
Do[s=DivisorSigma[1, n]/EulerPhi[n]; If[ !IntegerQ[s]&&!PrimeQ[n], Print[n]], {n, 1, 256}]
|
|
CROSSREFS
|
Cf. A020492, A078538, A078539, A078540.
Sequence in context: A127221 A020522 A037130 this_sequence A084128 A044047 A105487
Adjacent sequences: A078540 A078541 A078542 this_sequence A078544 A078545 A078546
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Dec 04 2002
|
|
|
Search completed in 0.002 seconds
|
