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 A072135 Least m such that sqrt(m) has a period 2n continued fraction expansion whose palindrome part concatenates to a palindromic prime. 1

%I

%S 23,22,234,115,1208,212,1269,999,7370,5019,3087,244,2329,2171,147112,

%T 90155,165407,7939,57451,69224,62064,19503,19844,563298,265095,

%U 14759823,121726,167817,97100,808386,7353035,1231680,201722,4754844,91904459

%N Least m such that sqrt(m) has a period 2n continued fraction expansion whose palindrome part concatenates to a palindromic prime.

%H Jon E. Schoenfield, <a href="/A072135/a072135.txt">The continued fraction for each term up through a(49)</a>

%e 23 is in the sequence because it is the first followed by 47, 96, 98, 119, 128, ... all exhibiting the following property:sqrt(23) = [4;1, 3, 1, 8], sqrt(47) = [6;1, 5, 1, 12], sqrt(96) = [9;1, 3, 1, 18], sqrt(98) = [9;1, 8, 1, 18], sqrt(119) = [10;1, 9, 1, 20], sqrt(128) = [11;3, 5, 3, 22], ... i.e. the continued fraction expansion of their square roots have palindrome parts which concatenate respectively to the 3-digit palprimes 131, 151, 131, 181, 191, 353, ...

%K hard,nice,nonn,base

%O 2,1

%A _Lekraj Beedassy_, Jun 26 2002

%E a(5)-a(36) from _Jon E. Schoenfield_, Apr 02 2010

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Last modified October 16 13:23 EDT 2019. Contains 328084 sequences. (Running on oeis4.)