cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A035126 Squares when digits rotated right once remain square.

Original entry on oeis.org

1, 4, 9, 256, 441, 961, 16641, 48841, 61009, 66564, 1127844, 2537649, 3857296, 4932841, 182682256, 298840369, 342842256, 392872041, 493772841, 787588096, 877996161, 10766967696, 33255899044, 49382172841, 74825772849
Offset: 1

Views

Author

Patrick De Geest, Nov 15 1998

Keywords

Comments

Those resulting in leading zeros excluded.

Examples

			2221^2 = 4932841 -> 1493284 = 1222^2. Note that the root behaves accordingly!
		

Crossrefs

Programs

  • Magma
    [k:k in [m^2:m in [1..10^6]]| IsSquare(Seqint( (Intseq(Floor(k/10)) cat  [ Intseq(k)[1]])))]; // Marius A. Burtea, Oct 08 2019
    
  • Mathematica
    Select[Range[300000]^2,IntegerQ[Sqrt[FromDigits[RotateRight[ IntegerDigits[ #]]]]]&] (* Harvey P. Dale, Mar 22 2015 *)
  • Python
    from itertools import count, islice
    from sympy.solvers.diophantine.diophantine import diop_DN
    def A035126_gen(): # generator of terms
        for l in count(0):
            l1, l2 = 10**(l+1), 10**l
            yield from sorted(set(x**2 for z in (diop_DN(10,m*(1-l1)) for m in range(10)) for x, y in z if l1 >= x**2 >= l2))
    A035126_list = list(islice(A035126_gen(),30)) # Chai Wah Wu, Apr 23 2022

Formula

a(n) = A045877(n)^2. - R. J. Mathar, Jan 25 2017

A045878 Numbers k such that rotating digits of k^2 left once still yields a square.

Original entry on oeis.org

1, 2, 3, 12, 14, 25, 108, 122, 216, 310, 1222, 2028, 2527, 3042, 11802, 12222, 13704, 24865, 25185, 26053, 30494, 122222, 208148, 247137, 312222, 1125786, 1222222, 1325080, 2084388, 2551071, 3025794, 3037736, 3126582, 10716846, 10787208
Offset: 1

Views

Author

Keywords

Comments

Squares resulting in leading zeros are excluded.
A090843 is a subsequence. - Chai Wah Wu, Apr 23 2022

Examples

			11303148^2 = {1}27761154709904 -> 277611547099041{1} = 16661679^2.
		

Crossrefs

Programs

  • Mathematica
    rlsQ[n_]:=Module[{idnrl=RotateLeft[IntegerDigits[n^2]]},First[idnrl]>0 && IntegerQ[Sqrt[FromDigits[idnrl]]]]; Select[Range[11000000],rlsQ] (* Harvey P. Dale, Nov 03 2013 *)
  • Python
    from itertools import count, islice
    from sympy.solvers.diophantine.diophantine import diop_DN
    def A045878_gen(): # generator of terms
        for l in count(0):
            l1, l2 = 10**(l+1), 10**l
            yield from sorted(set(abs(y) for z in (diop_DN(10,m*(1-l1)) for m in range(10)) for x, y in z if l1 >= x**2 >= l2))
    A045878_list = list(islice(A045878_gen(), 30)) # Chai Wah Wu, Apr 23 2022

Extensions

More terms from Patrick De Geest, Nov 15 1998

A035128 Rotating digits of a(n)^3 right once still yields a cube.

Original entry on oeis.org

1, 2, 5, 379
Offset: 1

Views

Author

Patrick De Geest, Nov 15 1998

Keywords

Comments

Cubes resulting in leading zeros excluded.

Examples

			379^3 = 54439939 -> 95443993 = 457^3.
		

Crossrefs

Programs

  • Magma
    [k:k in [1..100000]| IsPower(Seqint((Intseq(Floor(k^3/10)) cat [Intseq(k^3)[1]])),3)]; // Marius A. Burtea, Oct 08 2019
  • Mathematica
    Select[Range[500], IntegerQ @ Surd[FromDigits @ RotateRight @ IntegerDigits[#^3], 3] &] (* Amiram Eldar, Oct 08 2019 *)
Showing 1-3 of 3 results.