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A078662
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Number of balanced numbers <= 2^n.
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1
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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; refs; listen; history; internal format)
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OFFSET
| 0,2
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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.
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MATHEMATICA
| k = 1; c = 0; Do[ While[k <= 2^n, If[ IntegerQ[ DivisorSigma[1, k]/EulerPhi[k]], c++ ]; k++ ]; Print[c], {n, 0, 24}]
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CROSSREFS
| Cf. A020492, A078555.
Sequence in context: A188190 A026808 A003508 * A050048 A122456 A186243
Adjacent sequences: A078659 A078660 A078661 * A078663 A078664 A078665
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Dec 06 2002
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 14 2002
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