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Right half of periodic part of decimal expansion of 1/p for those primes having a periodic part of even length.
4

%I #6 Mar 30 2012 18:50:37

%S 857,0,230,41176470,473684210,56521739130,65517241379310,

%T 78723404255319148936170,83050847457627118644067796610,

%U 836065573770491803278688524590,8630,8876404494382022471910

%N Right half of periodic part of decimal expansion of 1/p for those primes having a periodic part of even length.

%C a(n) = A086999(n) mod 10^A087000(n); A055642(a(n))=A087000(n);

%C A087001(n) + a(n) = 10^A087000(n) - 1.

%D H. Rademacher and O. Toeplitz, Von Zahlen und Figuren (Springer 1930, reprinted 1968), ch. 19, Die periodischen Dezimalbrueche.

%H <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n.</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MidysTheorem.html">Midy's Theorem</a>

%e p=19: A086999(5)=526315789473684210 -> [526315789][473684210] ->

%e A087001(5)=526315789, A087002(5)=473684210,

%e A087001(5)+A087002(5)=526315789+473684210=999999999.

%K nonn,base

%O 1,1

%A _Reinhard Zumkeller_, Jul 29 2003