login
This site is supported by donations to The OEIS Foundation.

 

Logo

The October issue of the Notices of the Amer. Math. Soc. has an article about the OEIS.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A034935 Successive approximations to 5-adic integer sqrt(-1). 5
0, 2, 7, 57, 182, 2057, 14557, 45807, 280182, 6139557, 25670807, 123327057, 5006139557, 11109655182, 102662389557, 407838170807, 3459595983307, 79753541295807, 365855836217682, 2273204469030182, 49956920289342682 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

This is the root congruent to 2 mod 5.

REFERENCES

J. H. Conway, The Sensual Quadratic Form, p. 118.

K. Mahler, Introduction to p-Adic Numbers and Their Functions, Cambridge, 1973, p. 35.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..1121

FORMULA

Successive values of 2^(5^x) mod 5^x. - Joe K. Crump (joecr(AT)carolina.rr.com), Jan 20 2001

MATHEMATICA

Table[ PowerMod[2, 5^n, 5^n], {n, 0, 24}] // Union (* Jean-Fran├žois Alcover, Dec 03 2012, from formula given by Joe K. Crump *)

PROG

(PARI) sqrt(-1+O(5^40))

(PARI) {a(n) = local(k, x, y); for(i = 0, n, until( x != (y = truncate( sqrt( -1 + O(5^(k++))))), x = y)); x} /* Michael Somos, Mar 03 2008 */

CROSSREFS

Cf. A034939, A048898, A048899.

Sequence in context: A175818 A034939 A048898 * A294948 A178769 A121079

Adjacent sequences:  A034932 A034933 A034934 * A034936 A034937 A034938

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 19:01 EDT 2018. Contains 315270 sequences. (Running on oeis4.)