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
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 06 2002
EXTENSIONS
More terms from Robert G. Wilson v, Dec 14 2002
a(25)-a(37) from Donovan Johnson, Mar 03 2013
a(38)-a(49) from Amiram Eldar, Jun 04 2024
STATUS
approved