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A249633 Numbers whose squares remain squares when prepended with 1 and appended with 25 in base 10. 4

%I #14 Mar 08 2017 09:09:09

%S 285290,37501930,5986235584,6402200716,7097946940,2189113296470,

%T 533822715205534,120542200191255266,175167560462651234,

%U 1035777761966641262300,55811056504696202088334,87383897508158263975600,342433449090893699643070,356558269841736892522930

%N Numbers whose squares remain squares when prepended with 1 and appended with 25 in base 10.

%C Square roots of A249621.

%C a(34) >= 10^50. - _Hiroaki Yamanouchi_, Nov 22 2014

%C a(34) = 3894512793630238968387948459831502376753914222969510. - _Giovanni Resta_, Mar 08 2017

%H Chai Wah Wu and Hiroaki Yamanouchi, <a href="/A249633/b249633.txt">Table of n, a(n) for n = 1..33</a> (terms a(1)-a(27) from Chai Wah Wu)

%e 81390384100 = 285290^2 and 18139038410025 = 4258995^2.

%t a249633Q[n_Integer] :=

%t Module[{m, t}, m := ToString[n^2];

%t IntegerQ[Sqrt[ToExpression["1" <> m <> "25"]]]]; Select[Range[300000], a249633Q[#] &] (* _Michael De Vlieger_, Nov 06 2014 *)

%Y Cf. A249621.

%K nonn,base

%O 1,1

%A _Chai Wah Wu_, Nov 02 2014

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Last modified March 29 11:14 EDT 2024. Contains 371278 sequences. (Running on oeis4.)