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.

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A043107 Numbers k such that 0 and 2 occur juxtaposed in the base-5 representation of k but not of k-1.

Original entry on oeis.org

10, 27, 35, 50, 60, 77, 85, 102, 110, 127, 135, 152, 160, 175, 185, 202, 210, 227, 235, 250, 277, 285, 300, 310, 327, 335, 352, 360, 377, 385, 402, 410, 425, 435, 452, 460, 477, 485, 502, 510, 527, 535, 550, 560, 577, 585, 602
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.

Programs

  • Maple
    has02:= proc(n) local L,i,state;
      L:= convert(n,base,5);
      state:= 1;
      for i from 1 to nops(L) do
        if L[i] = 0 then
          if state = 2 then return true
          else state:= 0
          fi
        elif L[i] = 2 then
          if state = 0 then return true
          else state:= 2
          fi
        else state:= 1;
        fi
      od;
      false
    end proc:
    H:= select(has02, {$1..1001}):
    sort(convert(H minus map(`+`,H,1),list)); # Robert Israel, Jan 20 2019
  • Mathematica
    With[{s = Partition[Array[IntegerDigits[#, 5] &, 602], 2, 1]}, Map[FromDigits[#, 5] &, Select[s, And[And[SequenceCount[#1, {0, 2}] == 0, SequenceCount[#1, {2, 0}] == 0], Or[SequenceCount[#2, {0, 2}] > 0, SequenceCount[#2, {2, 0}] > 0]] & @@ # &][[All, -1]] ] ] (* Michael De Vlieger, Jan 20 2019 *)

A043356 Numbers having four 1's in base 5.

Original entry on oeis.org

156, 656, 756, 776, 780, 782, 783, 784, 786, 791, 796, 806, 831, 856, 906, 1031, 1156, 1406, 2031, 2656, 3156, 3256, 3276, 3280, 3282, 3283, 3284, 3286, 3291, 3296, 3306, 3331, 3356, 3406, 3531, 3656, 3756, 3776, 3780
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091 (numbers in base 5).

Programs

  • Maple
    F:= proc(d,m) option remember;
      local A,B;
      if m > d then return [] fi;
      if d = 0 then return [0] fi;
      A:= seq(seq(seq(t+i*5^(d-1),t=procname(dd,m)),dd = 0..d-1),i=2..4);
      if m = 0 then [A]
      else [seq(seq(t+5^(d-1),t=procname(dd,m-1)),dd=0..d-1),A]
      fi
    end proc:
    map(op,[seq(F(d,4),d=4..6)]); # Robert Israel, Jul 02 2018
  • Mathematica
    Select[Range[4000],DigitCount[#,5,1]==4&] (* Harvey P. Dale, Apr 28 2025 *)
  • PARI
    isok(n) = #select(x->(x==1), digits(n, 5)) == 4; \\ Michel Marcus, Jul 02 2018

A043364 Numbers having four 3's in base 5.

Original entry on oeis.org

468, 1093, 1718, 1968, 2093, 2218, 2268, 2293, 2318, 2328, 2333, 2338, 2340, 2341, 2342, 2344, 2348, 2368, 2468, 2968, 3593, 4218, 4843, 5093, 5218, 5343, 5393, 5418, 5443, 5453, 5458, 5463, 5465, 5466, 5467, 5469, 5473
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.

Programs

  • PARI
    isok(k) = #select(x->(x==3), digits(k, 5)) == 4; \\ Michel Marcus, Apr 24 2021

A043532 Number of distinct base-5 digits of n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 2, 2, 3, 3, 3, 2, 1, 2, 2, 2, 3, 2, 2, 3, 3, 3, 2, 3, 2, 3, 3, 2, 3, 3, 2, 2, 3, 2, 3, 3, 3, 2, 2, 3, 3, 2, 2, 1, 2, 2, 3, 3, 2, 2, 3, 3, 3, 2, 3, 2, 2, 3, 3, 2, 3, 3, 2, 3, 2, 3, 3, 3, 2, 2, 3, 2
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.

Programs

  • Mathematica
    f[n_]:=Length[Select[DigitCount[n,5],#!=0&]]; Array[f,100] (* Harvey P. Dale, May 11 2011 *)

A043605 Numbers whose base-5 representation has exactly 5 runs.

Original entry on oeis.org

651, 652, 653, 654, 660, 661, 663, 664, 665, 666, 667, 669, 670, 671, 672, 673, 676, 677, 678, 679, 680, 682, 683, 684, 690, 691, 692, 694, 695, 696, 697, 698, 701, 702, 703, 704, 705, 707, 708, 709, 710, 711, 713, 714, 720
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.

Programs

  • Maple
    fBC:= proc(b,c) local t,i,j,m;
        m:= 1/5; t:= 0:
        for i from 1 to 5 do
           for j from 1 to c[i] do
             m:= 5*m;
             t:= t + b[i]*m;
        od od;
      t
    end proc:
    F:= proc(n) local Res, a,b,c, q, B,C;
      Res:= NULL;
      B:= [seq(seq(seq(seq(seq([a[1],a[2],a[3],a[4],a[5]],a[1]=subs(a[2]=NULL,[$0..4])),a[2]=subs(a[3]=NULL,[$0..4])),a[3]=subs(a[4]=NULL,[$0..4])),a[4]=subs(a[5]=NULL,[$0..4])),a[5]=1..4)];
      sort([seq(seq(fBC(b,c),b=B),c=combinat:-composition(n,5))])
    end proc:
    op(F(5)),op(F(6)); # Robert Israel, Jan 22 2019
  • Mathematica
    Select[Range[1000],Length[Split[IntegerDigits[#,5]]]==5&] (* Harvey P. Dale, Jan 02 2014 *)

A045161 Numbers whose base-5 representation contains exactly one 0 and no 1's.

Original entry on oeis.org

0, 10, 15, 20, 52, 53, 54, 60, 65, 70, 77, 78, 79, 85, 90, 95, 102, 103, 104, 110, 115, 120, 262, 263, 264, 267, 268, 269, 272, 273, 274, 302, 303, 304, 310, 315, 320, 327, 328, 329, 335, 340, 345, 352, 353, 354, 360, 365, 370, 387
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.

Programs

  • Mathematica
    Select[Range[0, 400], DigitCount[#, 5, 0]==1 && DigitCount[#, 5, 1]==0 &] (* Vincenzo Librandi, Jun 29 2019 *)

Extensions

a(1) = 0 inserted by Georg Fischer, Jun 28 2019

A045177 Numbers whose base-5 representation contains exactly one 0 and one 2.

Original entry on oeis.org

10, 27, 35, 51, 53, 54, 55, 65, 70, 77, 85, 102, 110, 132, 136, 138, 139, 142, 147, 152, 160, 176, 178, 179, 180, 190, 195, 202, 210, 227, 235, 256, 258, 259, 266, 268, 269, 271, 273, 274, 276, 278, 279, 280, 290, 295, 326, 328, 329, 330, 340, 345, 351, 353
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.
Subsequence of A039284.

Programs

  • Python
    from sympy.ntheory import count_digits
    def ok(n): c = count_digits(n, b=5); return c[0] == c[2] == 1
    print([k for k in range(354) if ok(k)]) # Michael S. Branicky, Oct 27 2021

A045187 Numbers whose base-5 representation contains exactly three 0's and three 2's.

Original entry on oeis.org

6262, 6302, 6310, 6502, 6510, 6550, 7502, 7510, 7550, 7750, 15687, 15887, 15927, 15935, 16887, 16927, 16935, 17127, 17135, 17175, 21887, 21927, 21935, 22127, 22135, 22175, 23127, 23135, 23175, 23375, 31287, 31307
Offset: 1

Views

Author

Keywords

Examples

			6262_10 = 200022_5.
		

Crossrefs

Cf. A007091.

Programs

  • Mathematica
    Select[Range[35000],DigitCount[#,5,0]==DigitCount[#,5,2]==3&] (* Harvey P. Dale, Jul 23 2014 *)

A045203 Numbers whose base-5 representation contains no 0's and exactly one 4.

Original entry on oeis.org

4, 9, 14, 19, 21, 22, 23, 34, 39, 44, 46, 47, 48, 59, 64, 69, 71, 72, 73, 84, 89, 94, 96, 97, 98, 106, 107, 108, 111, 112, 113, 116, 117, 118, 159, 164, 169, 171, 172, 173, 184, 189, 194, 196, 197, 198, 209, 214, 219, 221, 222, 223
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007091.

Programs

  • Mathematica
    Select[Range[300],DigitCount[#,5,0]==0&&DigitCount[#,5,4]==1&] (* Harvey P. Dale, Jun 24 2014 *)

A045207 Numbers whose base-5 representation contains exactly one 0 and one 4.

Original entry on oeis.org

20, 29, 45, 54, 70, 79, 95, 101, 102, 103, 105, 110, 115, 134, 139, 144, 146, 147, 148, 154, 170, 179, 195, 204, 220, 226, 227, 228, 230, 235, 240, 259, 264, 269, 271, 272, 273, 279, 295, 304, 320, 329, 345, 351, 352, 353, 355
Offset: 1

Views

Author

Keywords

Comments

Subset of A039286. - R. J. Mathar, Oct 20 2008

Crossrefs

Cf. A007091.

Programs

  • Maple
    F:= proc(d) local S, i,j;
       # to get all d-digit members
       S:= select(t -> t[d]<>0, map(op@combinat:-permute,[seq(seq([0,4,1$i,2$j,3$(d-2-i-j)],j=0..d-2-i),i=0..d-2)]));
       sort(map(t -> add(t[i]*5^(i-1),i=1..d), S))
    end proc:
    seq(op(F(d)),d=2..5); # Robert Israel, Aug 02 2020
  • Mathematica
    Select[Range[400],DigitCount[#,5,0]==DigitCount[#,5,4]==1&] (* Harvey P. Dale, Nov 10 2017 *)
Previous Showing 101-110 of 321 results. Next