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 A178836 Numbers n such that the period of 1/n equals the period of 1/R(n), where R(n) (A004086) is the reversal of n. 0

%I

%S 3,7,9,11,33,77,99,101,111,121,131,141,151,161,171,181,191,303,313,

%T 323,333,343,353,363,373,383,393,707,717,727,737,747,757,767,777,787,

%U 797,909,919,929,939,949,959,969,979,989,999,1001,1111,1221,1331,1441,1551

%N Numbers n such that the period of 1/n equals the period of 1/R(n), where R(n) (A004086) is the reversal of n.

%C Non-palindromic numbers are included in this sequence :

%C {3267, 3927, 7293, 7632,...}

%e 3267 is in the sequence because period (1/3267) = 66 and also period(1/7623) = 66.

%e 3927 is in the sequence because period (1/3927) = 48 and also period(1/7293) = 48.

%p with(numtheory): nn:=8000:for n from 3 to nn do: s:=0:l:=length(n):for q from 0 to l-1 do:x:=iquo(n,10^q):y:=irem(x,10):s:=s+y*10^(l-1-q): od: indic1:=0:for p from 1 to nn do:if irem(10^p, n) = 1 and gcd(n, 5) = 1 and indic1=0 then pp:=p: indic1:=1:else fi:od: indic2:=0:for p from 1 to nn do:if irem(10^p, s) = 1 and gcd(s, 5) = 1 and indic2=0 then ppp:=p:indic2:=1:else fi:od: if pp=ppp and indic1=1 and indic2=1 then print(n):else fi:od:

%Y Cf. A004086, A045572, A002329.

%K nonn,base

%O 1,1

%A _Michel Lagneau_, Jun 16 2010

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Last modified August 7 15:47 EDT 2022. Contains 355994 sequences. (Running on oeis4.)