Hashgraph nodes must be able to calculate the influence of other nodes during the virtual voting process and calculation of the median timestamp of transactions. In a permissioned deployment of hashgraph, that influence will depend on the total number of nodes, and so nodes will need to know that value. Of course, in a permissioned deployment, this is not an issue as new nodes will join only after a provisioning process - part of which would be updating the network on the new member and so larger network size. On the other hand, in Hedera's stake-weighted deployment of hashgraph, a node's influence is determined by the node's stake as a fraction of the total stake (which is the total number of hbars) and not the number of nodes. The first number in this calculation is readily available from the ledger, the second is the constant 50b. Consequently, in Hedera, the number of nodes is irrelevant to the consensus calculation.
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