A383027 a(n) is the number whose reversed n-digit square is the largest among all reversals of n-digit squares.

3, 7, 17, 83, 167, 583, 1833, 8167, 10583, 41833, 191833, 489417, 1989417, 9958167, 25041833, 74958167, 125041833, 831989417, 1625041833, 9874958167, 15831989417, 65831989417, 309874958167, 834168010583, 1809874958167, 6809874958167, 29165831989417, 51809874958167, 179165831989417

Offset

1,1

Links

Table of n, a(n) for n=1..29.

Example

a(3)=17 because 982 (reverse of 17^2=289) is the largest reverse of all 3-digit squares.

Mathematica

a[n_]:=Module[{s=Ceiling[Sqrt[10^(n-1)]]}, max=IntegerReverse[s^2];
For[k=s, k<=Floor[Sqrt[(10^n-1)]], k++, t=IntegerReverse[k^2];
If[t>max, max=t; s=k]]; s]; Table[a[n], {n, 10}]

Crossrefs

Cf. A002942.

Sequence in context: A246764 A128343 A106877 * A041949 A222452 A218165

Adjacent sequences: A383024 A383025 A383026 * A383028 A383029 A383030

Keyword

nonn,base,easy

Author

Zhining Yang, Apr 13 2025

Status

approved