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Consider pairs (k,m) such that k^2 begins with a 1 and when the 1 is changed to a 2 we again get a square, m^2; sequence gives values of k for primitive solutions.
2

%I #16 Feb 06 2019 02:32:14

%S 105,3375,14025,326625,10846875,43708125,1015903125,34856484375,

%T 136203890625,111998513671875,424408358203125,359825755224609375,

%U 1322343959384765625,1155912765076904296875,4119741961077392578125,3712890686865325927734375

%N Consider pairs (k,m) such that k^2 begins with a 1 and when the 1 is changed to a 2 we again get a square, m^2; sequence gives values of k for primitive solutions.

%C Primitive here means that if (k,m) is a solution, solutions like (10^t*k,10^t*m) are ignored. - _Sean A. Irvine_, Feb 05 2019

%D Posting by Noam D. Elkies to netnews circa Oct 15 1992.

%H Sean A. Irvine, <a href="/A018233/b018233.txt">Table of n, a(n) for n = 1..40</a>

%H Noam D. Elkies, <a href="http://faqs.cs.uu.nl/na-dir/puzzles/archive/pickover/part2.html">Cliff Puzzle 8: Squares and Squares and Squares</a>, rec.puzzles Archive (pickover), part 29 of 35, 17 Aug 1993.

%Y Cf. A018232.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_

%E Missing terms inserted and more terms from _Sean A. Irvine_, Feb 05 2019