268207domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumbers n such that (10^n + 1)/11 is a prime.at n=10A001562Sum of Gaussian binomial coefficients for q=22.at n=4A015214Numbers n such that (10^n + 1)/11 is prime and can be written in the form a^2 + 7*b^2.at n=5A216531Prime numbersat n=23503