A115690 Squares whose digit reversal is a powerful(1) number (A001694).

1, 4, 9, 100, 121, 144, 169, 400, 441, 484, 576, 676, 900, 961, 1089, 9801, 10000, 10201, 10404, 10609, 12100, 12321, 12544, 12769, 14400, 14641, 14884, 16900, 25281, 27225, 40000, 40401, 40804, 44100, 44521, 44944, 48400, 48841, 57600

Offset

1,2

Comments

If x is a member, then so is 100*x. - Robert Israel, Mar 16 2020

Links

Robert Israel, Table of n, a(n) for n = 1..1500

Formula

Trivially, n^2 <= a(n) <= 100^(n-1). - Charles R Greathouse IV, Nov 01 2022

Example

25281=159^2 and 18252=2^2*3^3*13^2 is powerful.

Maple

filter:= proc(n) local L, i, x;
  L:= convert(n, base, 10);
  x:=add(L[-i]*10^(i-1), i=1..nops(L));
  andmap(t -> t[2]>=2, ifactors(x)[2]):
end proc:select(filter, [seq(i^2, i=1..10^4)]); # Robert Israel, Mar 16 2020

Prog

(PARI) is(k) = ispowerful(fromdigits(Vecrev(digits(k))));
select(is, vector(300, n, n^2)) \\ Michel Marcus, Nov 01 2022

Crossrefs

Subsequence of A115656.

A033294 is a subsequence, and the main entry for this sequence.

Cf. A001694, A115689.

Sequence in context: A335088 A247009 A245241 * A115689 A061457 A069707

Adjacent sequences: A115687 A115688 A115689 * A115691 A115692 A115693

Keyword

nonn,base

Author

Giovanni Resta, Jan 31 2006

Status

approved