|
Search: id:A078662
|
|
|
| A078662 |
|
Number of balanced numbers <= 2^n. |
|
+0
2
|
|
| 1, 2, 3, 4, 7, 8, 11, 14, 19, 24, 33, 39, 54, 69, 91, 122, 160, 206, 270, 346, 451, 575, 737, 962, 1260
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
EXAMPLE
|
There are nine balanced numbers between 512 and 1024: {570,594,616,630,714,744,812,840,910}, so a(10)= 9+a(9) = 33.
|
|
MATHEMATICA
|
k = 1; c = 0; Do[ While[k <= 2^n, If[ IntegerQ[ DivisorSigma[1, k]/EulerPhi[k]], c++ ]; k++ ]; Print[c], {n, 0, 24}]
|
|
CROSSREFS
|
Cf. A020492, A078555.
Sequence in context: A065294 A026808 A003508 this_sequence A050048 A122456 A073882
Adjacent sequences: A078659 A078660 A078661 this_sequence A078663 A078664 A078665
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Dec 06 2002
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 14 2002
|
|
|
Search completed in 0.002 seconds
|
