OFFSET
0,2
COMMENTS
For n > 0, a(n) is the unique solution to x^2 == 5 (mod 11^n) in the range [0, 11^n - 1] and congruent to 7 modulo 11.
A321076 is the approximation (congruent to 4 mod 11) of another square root of 5 over the 11-adic field.
LINKS
Wikipedia, p-adic number
EXAMPLE
7^2 = 49 = 5 + 4*11.
73^2 = 5329 = 5 + 44*11^2 = 5 + 4*11^3.
PROG
(PARI) a(n) = truncate(-sqrt(5+O(11^n)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Oct 27 2018
STATUS
approved