Help understanding frequency calculation for VCO Schematic in LM13700 Datasheet
Your math looks right. The datasheet must just have the frequency range wrong. The equation for the frequency comes from CV=IT, where V is the peak to peak voltage \$R_A\$ sees. So: 

T =  \$\frac{\text{C } V_{\text{pp}-\text{Ra}}}{I_{\text{c}}}\$ 

is the charging time of the capacitor. For the charge and discharge time, just multiply by 2. Invert to get the frequency. Also, just as you did, replace \$V_{\text{pp}-\text{Ra}}\$ by \$2 I_a R_a\$. To get: 

\$f_{\text{osc}}\$ = \$\frac{I_{\text{c}}}{4 \text{ C } I_a R_a}\$ 

Where \$I_a\$ = (15V+13.6V)/51k\$\Omega\$ ~ 0.58mA and \$I_c\$ = (15V+13.6V)/30k\$\Omega\$ ~ 0.95mA. 

For capacitance of 200pF, \$f_{\text{osc}}\$ would be about 401kHz.