A065808 Square of n has a smaller square as its final digits.

7, 8, 9, 10, 11, 12, 13, 15, 17, 18, 19, 20, 21, 22, 23, 25, 27, 28, 29, 30, 31, 32, 33, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 65, 67, 68, 69, 70, 71, 72, 73, 75, 77, 78, 79, 80, 81, 82, 83, 85, 87, 88

Offset

1,1

Comments

Includes all n >= 7 not == 4 or 6 (mod 10). - Robert Israel, Oct 24 2017

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= n ->
  ormap(t -> issqr(n^2 mod 10^t), [$1..ilog10(n^2)]):
select(filter, [$1..100]); # Robert Israel, Oct 24 2017

Mathematica

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

Prog

(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)

Crossrefs

A065807 gives the corresponding squares.

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

Sequence in context: A162787 A182308 A023388 * A250046 A062947 A194345

Adjacent sequences: A065805 A065806 A065807 * A065809 A065810 A065811

Keyword

base,easy,nonn

Author

Klaus Brockhaus, Nov 22 2001

Extensions

Offset changed to 1 by Robert Israel, Oct 24 2017

Status

approved