A065808 - OEIS

%I #12 Oct 24 2017 02:29:46

%S 7,8,9,10,11,12,13,15,17,18,19,20,21,22,23,25,27,28,29,30,31,32,33,35,

%T 37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,

%U 60,61,62,63,65,67,68,69,70,71,72,73,75,77,78,79,80,81,82,83,85,87,88

%N Square of n has a smaller square as its final digits.

%C Includes all n >= 7 not == 4 or 6 (mod 10). - _Robert Israel_, Oct 24 2017

%H Robert Israel, <a href="/A065808/b065808.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= n ->

%p   ormap(t -> issqr(n^2 mod 10^t), [$1..ilog10(n^2)]):

%p select(filter, [$1..100]); # _Robert Israel_, Oct 24 2017

%t ds[n_] := NestWhileList[FromDigits[Rest[IntegerDigits[#]]] &, n, # > 9 &]; Select[Range[4, 88], Or @@ IntegerQ /@ Sqrt[Rest[ds[#^2]]] &] (* _Jayanta Basu_, Jul 10 2013 *)

%o (PARI): a065808(m) = local(k, a, b, d, j, n, r); for(k=1, m, a=length(Str(n))-1; b=1; j=1; n=k^2; while(b, d=divrem(n, 10^j); if(d[1]>0&&issquare(d[2]), b=0; issquare(n, &r); print1(r, ","), if(j<a, j++, b=0)))) a065808(100)

%Y A065807 gives the corresponding squares.

%Y Cf. A065690, A050635, A050637, A050639, A065777, A065780, A065783, A065786, A065789, A065792.

%K base,easy,nonn

%O 1,1

%A _Klaus Brockhaus_, Nov 22 2001

%E Offset changed to 1 by _Robert Israel_, Oct 24 2017