Landau-Ramanujan constant

After its two independent discoverers, Edmund Landau and Srinivasa Ramanujan.

Landau-Ramanujan constant

1. (number theory) The constant of proportionality (approximately 0.7642) in the relationship between the number of positive integers less than x that are the sum of two square numbers, for large x, and the expression ${\displaystyle x/{\sqrt {\ln(x)}}.}$