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 1-10 of 12 results. Next

A054038 Numbers k such that k^2 contains every digit at least once.

Original entry on oeis.org

32043, 32286, 33144, 35172, 35337, 35757, 35853, 37176, 37905, 38772, 39147, 39336, 40545, 42744, 43902, 44016, 45567, 45624, 46587, 48852, 49314, 49353, 50706, 53976, 54918, 55446, 55524, 55581, 55626, 56532, 57321, 58413, 58455
Offset: 1

Views

Author

Asher Auel, Feb 28 2000

Keywords

Comments

There are 87 terms < 10^5; these are the n such that n^2 uses each digit exactly once. - David Wasserman, Feb 03 2005
The squares in this sequence are in A190682. - Bruno Berselli, May 23 2011

References

  • J.-M. De Koninck and A. Mercier, 1001 Problemes en Theorie Classique Des Nombres, Problem 239 pp. 39; 178, Ellipses Paris 2004.

Crossrefs

Programs

  • Magma
    IsA054038:=func< n | Seqset(Intseq(n^2)) eq {0,1,2,3,4,5,6,7,8,9} >; [ n: n in [1..60000] | IsA054038(n) ]; // Klaus Brockhaus, May 16 2011
    
  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=10 then f := [op(f),i] fi; od; f;
  • Mathematica
    A050278 = Select[FromDigits@#&/@Permutations[Range[0, 9], {10}], # > 10^9 &]; Sqrt[Select[A050278, IntegerQ[Sqrt[#]] &]] (* Alonso del Arte, Jun 18 2011, based on a program by Robert G. Wilson v *)
    Select[Sqrt[#]&/@FromDigits/@Select[Permutations[Range[0,9]],#[[1]]>0&], IntegerQ] (* Harvey P. Dale, May 26 2016 *)
  • PARI
    is(n)=#vecsort(Vec(Str(n^2)),,8)==10 \\ Charles R Greathouse IV, Jun 18 2011
    
  • Python
    def ok(n): return len(set(str(n**2))) == 10
    print([k for k in range(10**5) if ok(k)]) # Michael S. Branicky, Dec 23 2022

Extensions

More terms from David Wasserman, Feb 03 2005

A054037 Numbers k such that k^2 contains exactly 9 different digits.

Original entry on oeis.org

10124, 10128, 10136, 10214, 10278, 11826, 12363, 12543, 12582, 12586, 13147, 13268, 13278, 13343, 13434, 13545, 13698, 14098, 14442, 14676, 14743, 14766, 15353, 15681, 15963, 16549, 16854, 17252, 17529, 17778, 17816, 18072, 19023, 19377, 19569, 19629, 20089
Offset: 1

Views

Author

Asher Auel, Feb 28 2000

Keywords

Comments

There are three prime numbers {13147, 20089, 21397} and corresponding squares {172843609, 403567921, 457831609} necessarily contain zero (otherwise n and n^2 are divisible by 3). - Zak Seidov, Jan 18 2012

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=9 then f := [op(f),i] fi; od; f;
  • Mathematica
    okQ[n_] := Module[{n2=n^2}, Max[DigitCount[n2,10]]==1 && IntegerLength[n2]==9]; Select[Range[20000], okQ]  (* Harvey P. Dale, Mar 20 2011 *)
  • Python
    from itertools import count, islice
    def agen(): yield from (k for k in count(10**4) if len(set(str(k*k)))==9)
    print(list(islice(agen(), 37))) # Michael S. Branicky, May 24 2022

A054031 Numbers whose square contains exactly 3 distinct digits.

Original entry on oeis.org

13, 14, 16, 17, 18, 19, 23, 24, 25, 27, 28, 29, 31, 34, 35, 39, 40, 41, 45, 46, 47, 50, 56, 58, 60, 62, 63, 65, 67, 68, 70, 75, 76, 77, 80, 81, 83, 85, 90, 91, 92, 94, 97, 101, 102, 107, 108, 110, 111, 119, 120, 121, 122, 129, 131, 141, 149, 150, 162, 165
Offset: 1

Views

Author

Asher Auel, Feb 29 2000

Keywords

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=3 then f := [op(f),i] fi; od; f;
  • Mathematica
    t = {}; n = -1; While[Length[t] < 50, n++; If[Length[Union[IntegerDigits[n^2]]] == 3, AppendTo[t, n]]] (* T. D. Noe, Apr 26 2013 *)
    Select[Range[200],Length[Union[IntegerDigits[#^2]]]==3&] (* Harvey P. Dale, Aug 17 2014 *)
  • PARI
    is(n)=#Set(digits(n^2))==3 \\ Charles R Greathouse IV, Feb 11 2017

Formula

A235718(n) = a(n)^2. - Giovanni Resta, Apr 28 2017

A054032 Numbers n such that n^2 contains exactly 4 different digits.

Original entry on oeis.org

32, 33, 36, 37, 42, 43, 44, 48, 49, 51, 52, 53, 54, 55, 57, 59, 61, 64, 66, 69, 71, 72, 73, 74, 78, 79, 82, 84, 86, 87, 89, 93, 95, 96, 98, 99, 103, 104, 105, 106, 112, 114, 115, 123, 125, 127, 130, 132, 135, 138, 139, 140, 143, 145, 146, 151, 155, 156, 157, 158
Offset: 1

Views

Author

Asher Auel, Feb 29 2000

Keywords

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=4 then f := [op(f),i] fi; od; f;
  • Mathematica
    t = {}; n = -1; While[Length[t] < 50, n++; If[Length[Union[IntegerDigits[n^2]]] == 4, AppendTo[t, n]]] (* T. D. Noe, Apr 26 2013 *)
  • PARI
    is(n)=#Set(digits(n^2))==4 \\ Charles R Greathouse IV, Feb 11 2017

A054033 Numbers n such that n^2 contains exactly 5 different digits.

Original entry on oeis.org

113, 116, 117, 118, 124, 126, 128, 133, 134, 136, 137, 142, 144, 147, 148, 152, 153, 154, 169, 172, 174, 175, 176, 178, 179, 181, 186, 189, 191, 193, 195, 196, 198, 199, 203, 209, 213, 214, 217, 219, 224, 226, 228, 232, 233, 248, 252, 259, 267, 268, 269
Offset: 1

Views

Author

Asher Auel, Feb 29 2000

Keywords

Comments

The first 66 terms are the only ones whose squares contain no repeated digits. - Charles R Greathouse IV, Feb 09 2015

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=5 then f := [op(f),i] fi; od; f;
  • Mathematica
    Select[Range[101,500],Count[DigitCount[#^2],0]==5&] (* Harvey P. Dale, Feb 08 2015 *)
  • PARI
    is(n)=#Set(digits(n^2))==5 \\ Charles R Greathouse IV, Feb 08 2015

A054034 Numbers n such that n^2 contains exactly 6 different digits.

Original entry on oeis.org

322, 323, 324, 328, 352, 353, 364, 367, 374, 375, 397, 403, 405, 413, 416, 425, 442, 445, 456, 458, 463, 487, 504, 507, 508, 509, 529, 542, 557, 564, 567, 571, 572, 574, 584, 589, 591, 593, 597, 598, 616, 618, 621, 625, 626, 629, 634, 637, 639, 645, 647
Offset: 1

Views

Author

Asher Auel, Feb 29 2000

Keywords

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=6 then f := [op(f),i] fi; od; f;
  • Mathematica
    Select[Range[700],Count[DigitCount[#^2],0]==4&] (* Harvey P. Dale, May 10 2021 *)

A054035 Numbers n such that n^2 contains exactly 7 different digits.

Original entry on oeis.org

1017, 1023, 1024, 1027, 1028, 1036, 1037, 1042, 1113, 1117, 1164, 1175, 1176, 1197, 1228, 1267, 1268, 1277, 1302, 1307, 1323, 1328, 1343, 1352, 1355, 1375, 1395, 1405, 1428, 1433, 1441, 1442, 1444, 1463, 1541, 1593, 1594, 1628, 1646, 1648, 1701, 1706
Offset: 1

Views

Author

Asher Auel, Feb 29 2000

Keywords

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=7 then f := [op(f),i] fi; od; f;
  • Mathematica
    Select[Range[2000],Count[DigitCount[#^2],0]==3&] (* Harvey P. Dale, Jul 28 2012 *)

A054036 Numbers n such that n^2 contains exactly 8 different digits.

Original entry on oeis.org

3206, 3267, 3268, 3292, 3674, 3678, 3698, 3723, 3734, 4047, 4097, 4157, 4175, 4455, 4537, 4554, 4616, 4634, 4663, 4804, 4814, 4896, 4913, 4967, 4987, 5376, 5529, 5699, 5742, 5853, 5899, 5904, 5905, 5968, 6043, 6071, 6095, 6098, 6127, 6176, 6181, 6199
Offset: 1

Views

Author

Asher Auel, Feb 28 2000

Keywords

Examples

			3206 is in the sequence because 3206^2 = 10278436 and 10278436 contains exactly eight different digits: 0, 1, 2, 3, 4, 6, 7 and 8.
		

Crossrefs

Programs

  • Maple
    f := []; for i from 0 to 200 do if nops({op(convert(i^2,base,10))})=8 then f := [op(f),i] fi; od; f;
  • Mathematica
    Select[Range[7000],Count[DigitCount[#^2],0]==2&] (* Harvey P. Dale, Aug 10 2017 *)

A217368 Smallest number having a power that in decimal has exactly n copies of all ten digits.

Original entry on oeis.org

32043, 69636, 643905, 421359, 320127, 3976581, 47745831, 15763347, 31064268, 44626422, 248967789, 85810806, 458764971, 500282265, 2068553967, 711974055, 2652652791, 901992825, 175536645, 3048377607, 3322858521, 1427472867, 3730866429, 9793730157
Offset: 1

Views

Author

James G. Merickel, Oct 01 2012

Keywords

Comments

The exponents that produce the number with a fixed number of copies of each digit are listed in sequence A217378. See there for further comments.
Since we allow A217378(n)=1, the sequence is well defined, with the upper bound a(n) <= 100...99 ~ 10^(10n-1) (n copies of each digit, sorted in increasing order, except for one "1" permuted to the first position). - M. F. Hasler, Oct 05 2012
What is the minimum value of a(n)? Can it be proved that a(n) > 2 for all n? - Charles R Greathouse IV, Oct 16 2012

Examples

			The third term raised to the fifth power (A217378(3)=5), 643905^5 = 110690152879433875483274690625, has three copies of each digit (in its decimal representation), and no number smaller than 643905 has a power with this feature.
		

Crossrefs

Programs

  • Mathematica
    f[n_] := Block[{k = 2, t = Table[n, {10}], r = Range[0, 9]}, While[c = Count[ IntegerDigits[k^Floor[ Log[k, 10^(10 n)]]], #] & /@ r; c != t, k++]; k] (* Robert G. Wilson v, Nov 28 2012 *)
  • PARI
    is(n,k)=my(v);for(e=ceil((10*n-1)*log(10)/log(k)), 10*n*log(10)/log(k), v=vecsort(digits(k^e)); for(i=1,9,if(v[i*n]!=i-1 || v[i*n+1]!=i, return(0))); return(1)); 0
    a(n)=my(k=2); while(!is(n,k),k++); k \\ Charles R Greathouse IV, Oct 16 2012

Extensions

a(13)-a(14) from James G. Merickel, Oct 06 2012 and Oct 08 2012
a(15)-a(16) from Charles R Greathouse IV, Oct 17 2012
a(17)-a(19) from Charles R Greathouse IV, Oct 18 2012
a(20) from Charles R Greathouse IV, Oct 22 2012
a(21)-a(24) from Giovanni Resta, May 05 2017

A247794 a(n)^3 is the least cube to contain exactly n distinct digits.

Original entry on oeis.org

0, 3, 5, 12, 22, 59, 135, 289, 1018, 2326
Offset: 1

Views

Author

Derek Orr, Sep 23 2014

Keywords

Comments

"...at least n..." and "...exactly n..." yield the same sequence (i.e. this sequence is strictly increasing).

Crossrefs

Cf. A054039.

Programs

Showing 1-10 of 12 results. Next