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A321076 One of the two successive approximations up to 11^n for 11-adic integer sqrt(5). Here the 4 (mod 11) case (except for n = 0). 2
0, 4, 48, 1258, 6582, 6582, 1456041, 10313846, 166211214, 1666723381, 18172357218, 95984631021, 2663789666520, 24632788303567, 162723636879291, 542473470462532, 33960458825787740, 493457757461509350, 3020692899957978205, 58619866034880293015, 547892589622196663343 (list; graph; refs; listen; history; text; internal format)
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 4 modulo 11.

A321077 is the approximation (congruent to 7 mod 11) of another square root of 5 over the 11-adic field.

LINKS

Table of n, a(n) for n=0..20.

Wikipedia, p-adic number

FORMULA

For n > 0, a(n) = 11^n - A321077(n).

a(n) = Sum_{i=0..n-1} A321078(i)*11^i.

EXAMPLE

4^2 = 16 = 5 + 1*11.

48^2 = 2304 = 5 + 19*11^2.

1258^2 = 1582564 = 5 + 1189*11^3.

PROG

(PARI) a(n) = truncate(sqrt(5+O(11^n)))

CROSSREFS

Cf. A321077, A321078.

Sequence in context: A211045 A296838 A211049 * A166231 A191952 A013145

Adjacent sequences:  A321073 A321074 A321075 * A321077 A321078 A321079

KEYWORD

nonn

AUTHOR

Jianing Song, Oct 27 2018

STATUS

approved

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Last modified January 19 00:40 EST 2020. Contains 331030 sequences. (Running on oeis4.)