The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #15 Sep 25 2023 07:50:22
%S 1,6,9,744,4179600,8448511339584,5768007101259200000000000049,
%T 5174534068654382362457957919012519218990703784333328400,
%U 2738806678866818978778889262772030983678218158753649709561749318814684327986697592167893627634348717226004356
%N Least multiple of n such that every concatenation a(1)...a(i) for 1 <= i <= n is a perfect square.
%e 1, 16, 169, 169744 are all squares. [corrected by _Harvey P. Dale_, Aug 06 2019]
%o (PARI) f(n, num) = local(d, x); d = 1; while (1, x = sqrtint(num*10^d + 10^(d - 1) - 1) + 1; while (x^2 < (num + 1)*10^d && (x^2%10^d)%n, x++); if (x^2 < (num + 1)*10^d, return([x^2, x^2%10^d])); d++);
%o num = 0; for (n = 1, 10, p = f(n, num); print1(p[2], ", "); num = p[1]); \\ _David Wasserman_, Dec 03 2008
%Y Cf. A061110.
%K base,nonn
%O 1,2
%A _Amarnath Murthy_, Aug 04 2005
%E More terms from _David Wasserman_, Dec 03 2008
%E Clarified definition. - _N. J. A. Sloane_, Sep 25 2023