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A018248 The 10-adic integer x = ...1787109376 satisfies x^2 = x. +0
12
6, 7, 3, 9, 0, 1, 7, 8, 7, 1, 8, 0, 0, 4, 7, 3, 4, 7, 7, 0, 6, 2, 2, 0, 0, 8, 3, 3, 9, 8, 5, 9, 9, 0, 9, 8, 3, 0, 1, 9, 6, 7, 6, 7, 5, 6, 7, 5, 2, 4, 4, 9, 9, 9, 8, 8, 1, 6, 3, 1, 9, 1, 4, 0, 9, 4, 3, 3, 8, 7, 3, 9, 9, 0, 1, 0, 9, 4, 1, 6, 0, 7, 9, 1, 0, 3, 8, 1, 9, 8, 0, 8, 6, 2, 9, 9, 6, 4, 0, 6, 9, 0, 6, 3, 7, 5, 3, 2 (list; graph; listen)
OFFSET

0,1

COMMENT

The 10-adic numbers a and b defined in A018247 and this sequence satisfy a^2=a, b^2=b, a+b=1, ab=0.

REFERENCES

W. W. R. Ball, Mathematical Recreations & Essays, N.Y. Macmillan Co, 1947.

R. Cuculiere, Jeux Mathematiques, in Pour la Science, No. 6 (1986), 10-15.

M. Kraitchik, Sphinx, 1935, p. 1.

A. M. Robert, A Course in p-adic Analysis, Springer, 2000; see pp. 63, 419.

LINKS

Paul D. Hanna, Table of n, a(n) for n = 0..999

Anonymous, Automorphic numbers (2)

Eric Weisstein's World of Mathematics, Automorphic numbers (1)

Index entries for sequences related to automorphic numbers

FORMULA

x = r^4 where r=...1441224165530407839804103263499879186432 (A120817). x = 10-adic limit_{n->infty} 6^(5^n). - Paul D. Hanna (pauldhanna(AT)juno.com), Jul 06 2006

EXAMPLE

x equals the limit of the (n+1) trailing digits of 6^(5^n):

6^(5^0)=(6), 6^(5^1)=77(76), 6^(5^2)=28430288029929701(376),...

x = ...9442576576769103890995893380022607743740081787109376.

MATHEMATICA

b = {6}; g[n_] := Block[{k = 0, c}, While[c = FromDigits[Prepend[b, k]]; Mod[c^2, 10^n] != c, k++ ]; b = Prepend[b, k]]; Do[ g[n], {n, 2, 105}]; Reverse[b]

PROGRAM

(PARI) {a(n)=local(b=6, v=[]); for(k=1, n+1, b=b^5%10^k; v=concat(v, (10*b\10^k))); v[n+1]} - Paul D. Hanna (pauldhanna(AT)juno.com), Jul 06 2006

CROSSREFS

A016090 gives associated automorphic numbers.

Cf. A018247, A033819.

The difference between this sequence & A018247 is A075693 and their product is A075693.

Cf. A120817, A120818, A091664.

Sequence in context: A154339 A139350 A092560 this_sequence A146485 A049254 A144028

Adjacent sequences: A018245 A018246 A018247 this_sequence A018249 A018250 A018251

KEYWORD

base,nonn

AUTHOR

Yoshihide Tamori (yo(AT)salk.edu)

EXTENSIONS

More terms from David W. Wilson (davidwwilson(AT)comcast.net). Comments from Michael Somos.

Edited by David W. Wilson, Sep 26, 2002

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Last modified November 25 14:45 EST 2009. Contains 167481 sequences.


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