A258682 Remove from n^2 all digits of n from left to right, in decimal representation.

0, 0, 4, 9, 16, 2, 3, 49, 64, 81, 0, 2, 44, 69, 96, 22, 25, 289, 324, 36, 40, 44, 484, 59, 576, 6, 76, 9, 74, 841, 90, 96, 104, 1089, 1156, 122, 129, 169, 1444, 1521, 160, 681, 176, 189, 1936, 202, 211, 2209, 230, 201, 20, 260, 704, 2809, 2916, 302, 313

Offset

0,3

Comments

a(A029783(n)) = A029783(n)^2; a(A189056(n)) < A189056(n)^2;

a(A178501(n)) = 0.

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Example

.    n   n^2 |  a(n)
. -----------+------
.   20   400 |    40
.   21   441 |    44
.   22   484 |   484
.   23   529 |    59
.   24   576 |   576
.   25   625 |     6
.   26   676 |    76  not 67, as digits of n are to be removed
.   27   729 |     9                                  from left to right
.   28   784 |    74
.   29   841 |   841
.   30   900 |    90  .

Mathematica

a[n_]:=Module[{idn=IntegerDigits[n], idnn=IntegerDigits[n^2], idn1},
idn1=DeleteCases[idn, m_/; MemberQ[Complement[idn, idnn], m]];
Do[If[First[Position[idnn, idn1[[i]]]]!= {}, idnn=Delete[idnn, First[Position[idnn, idn1[[i]]]]]],
{i, 1, Length[idn1]}]; FromDigits[idnn]]//Quiet;
a/@Range[0, 56] (* Ivan N. Ianakiev, Jun 11 2015 *)

Prog

(Haskell)
import Data.List (delete)
a258682 n = read ('0' : minus (show (n ^ 2)) (show n)) :: Int  where
   minus [] _  = []
   minus us [] = us
   minus (u:us) vs | elem u vs = minus us $ delete u vs
                   | otherwise = u : minus us vs

Crossrefs

Cf. A000290, A029783, A189056, A178501.

Sequence in context: A276191 A007893 A070446 * A070445 A070444 A120866

Adjacent sequences: A258679 A258680 A258681 * A258683 A258684 A258685

Keyword

nonn,base,look

Author

Reinhard Zumkeller, Jun 07 2015

Status

approved