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 14 results. Next

A131835 Numbers starting with 1.

Original entry on oeis.org

1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142
Offset: 1

Views

Author

Andrew Good (yipes_stripes(AT)yahoo.com), Jul 20 2007

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/9 and 5/9, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Subsequence of A011531.
Disjoint union of A045707 and A206286.
Cf. A000030, A000027, A002275, A262390 (permutation).

Programs

  • Haskell
    a131835 n = a131835_list !! (n-1)
    a131835_list = concat $
                   iterate (concatMap (\x -> map (+ 10 * x) [0..9])) [1]
    -- Reinhard Zumkeller, Jul 16 2014
    
  • Maple
    isA131835 := proc(n) if op(-1,convert(n,base,10)) = 1 then true; else false ; fi ; end: for n from 1 to 300 do if isA131835(n) then printf("%d, ",n) ; fi ; od : # R. J. Mathar, Jul 24 2007
  • Mathematica
    Select[Range[150], IntegerDigits[#][[1]] == 1 &] (* Amiram Eldar, Feb 27 2021 *)
  • PARI
    a(n, {base=10}) = my (o=1); while (n>o, n-=o; o*=base); return (o+n-1) \\ Rémy Sigrist, Jun 23 2017
    
  • PARI
    a(n) = n--; s = #digits(9*n+1); n + 8 * (10^(s-1))/9 + 1/9 \\ David A. Corneth, Jun 23 2017
    
  • PARI
    nxt(n) = my(d = digits(n+1)); if(d[1]==1, n+1, 10^#d) \\ David A. Corneth, Jun 23 2017
    
  • Python
    def A131835(n): return n+(10**(len(str(9*n-8))-1)<<3)//9 # Chai Wah Wu, Dec 07 2024

Formula

A000030(a(n)) = 1. - Reinhard Zumkeller, Jul 16 2014
a(A002275(n)+1) = 10^n for any n >= 0. - Rémy Sigrist, Jun 23 2017
a(n) = n + (8*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 16 2023

Extensions

More terms from R. J. Mathar, Jul 24 2007

A217394 Numbers starting with 2.

Original entry on oeis.org

2, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/18 and 10/27, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • Mathematica
    Select[Range[300], IntegerDigits[#][[1]] == 2 &] (* T. D. Noe, Oct 02 2012 *)
  • Python
    def agen():
      yield 2
      digits, adder = 1, 20
      while True:
        for i in range(10**digits): yield adder + i
        digits, adder = digits+1, adder*10
    g = agen()
    print([next(g) for i in range(54)]) # Michael S. Branicky, Feb 20 2021
    
  • Python
    def A217394(n): return n+(17*10**(len(str(9*n-8))-1))//9 # Chai Wah Wu, Dec 07 2024

Formula

a(n) = n + (17*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 15 2023

A217399 Numbers starting with 6.

Original entry on oeis.org

6, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 632, 633, 634, 635, 636, 637, 638, 639, 640, 641, 642
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/54 and 10/63, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • GAP
    Flat(List([0..2],n->List([0..10^n-1],k->6*10^n+k))); # Muniru A Asiru, Nov 21 2018
    
  • Magma
    [n: n in [1..1600] | Intseq(n)[#Intseq(n)] eq 6]; // Vincenzo Librandi, Nov 24 2018
    
  • Maple
    seq(seq(6*10^n+k, k=0..10^n-1),n=0..3); # Robert Israel, May 08 2017
  • Mathematica
    Select[Range[1000], IntegerDigits[#][[1]] == 6 &] (* T. D. Noe, Oct 02 2012 *)
  • PARI
    isok(n) = digits(n)[1] == 6; \\ Michel Marcus, May 08 2017
    
  • Python
    def A217399(n): return n+(53*10**(len(str(9*n-8))-1))//9 # Chai Wah Wu, Dec 07 2024

Formula

a(n) = n + (53*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 17 2023

A217397 Numbers starting with 4.

Original entry on oeis.org

4, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 400, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432, 433, 434, 435, 436, 437, 438, 439, 440, 441, 442
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/36 and 2/9, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], IntegerDigits[#][[1]] == 4 &] (* T. D. Noe, Oct 02 2012 *)
  • Python
    def A217397(n): return n+(35*10**(len(str(9*n-8))-1))//9 # Chai Wah Wu, Dec 07 2024

Formula

a(n) = n + (35*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 17 2023

A217400 Numbers starting with 7.

Original entry on oeis.org

7, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 700, 701, 702, 703, 704, 705, 706, 707, 708, 709, 710, 711, 712, 713, 714, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729, 730, 731, 732, 733, 734, 735, 736, 737, 738, 739, 740, 741, 742
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/63 and 5/36, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], IntegerDigits[#][[1]] == 7 &] (* T. D. Noe, Oct 02 2012 *)
  • Python
    def A217400(n): return n+(62*10**(len(str(9*n-8))-1))//9 # Chai Wah Wu, Dec 07 2024

Formula

a(n) = n + (62*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 17 2023

A217401 Numbers starting with 8.

Original entry on oeis.org

8, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810, 811, 812, 813, 814, 815, 816, 817, 818, 819, 820, 821, 822, 823, 824, 825, 826, 827, 828, 829, 830, 831, 832, 833, 834, 835, 836, 837, 838, 839, 840, 841, 842
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/72 and 10/81, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], IntegerDigits[#][[1]] == 8 &] (* T. D. Noe, Oct 02 2012 *)
  • Python
    def A217401(n): return n+(71*10**(len(str(9*n-8))-1))//9 # Chai Wah Wu, Dec 07 2024

Formula

a(n) = n + (71*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 17 2023

A217402 Numbers starting with 9.

Original entry on oeis.org

9, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911, 912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923, 924, 925, 926, 927, 928, 929, 930, 931, 932, 933, 934, 935, 936, 937, 938, 939, 940, 941, 942
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/81 and 1/9, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], IntegerDigits[#][[1]] == 9 &] (* T. D. Noe, Oct 02 2012 *)
  • Python
    def A217402(n): return n+(80*10**(len(str(9*n-8))-1))//9 # Chai Wah Wu, Dec 07 2024

Formula

a(n) = n + (80*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 17 2023

A217395 Numbers starting with 3.

Original entry on oeis.org

3, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 317, 318, 319, 320, 321, 322, 323, 324, 325, 326, 327, 328, 329, 330, 331, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342
Offset: 1

Views

Author

Jeremy Gardiner, Oct 02 2012

Keywords

Comments

The lower and upper asymptotic densities of this sequence are 1/27 and 5/18, respectively. - Amiram Eldar, Feb 27 2021

Crossrefs

Programs

  • Mathematica
    Select[Range[1000], IntegerDigits[#][[1]] == 3 &] (* T. D. Noe, Oct 02 2012 *)
  • PARI
    a(n) = n + 26*10^logint(9*n,10)\9; \\ Kevin Ryde, Mar 30 2021
  • Python
    def agen():
      yield 3
      digits, adder = 1, 30
      while True:
        for i in range(10**digits): yield adder + i
        digits, adder = digits+1, adder*10
    g = agen()
    print([next(g) for i in range(54)]) # Michael S. Branicky, Mar 30 2021
    
  • Python
    def A217395(n): return n+26*10**(len(str(9*n-8))-1)//9 # Chai Wah Wu, Sep 11 2024
    

Formula

a(n) = n + (26*10^floor(log_10(9*n-8))-8)/9. - Alan Michael Gómez Calderón, May 16 2023

A385700 Numbers such that when the leftmost digit is moved to the unit's place the result is divisible by 4.

Original entry on oeis.org

0, 4, 8, 21, 23, 25, 27, 29, 40, 42, 44, 46, 48, 61, 63, 65, 67, 69, 80, 82, 84, 86, 88, 201, 203, 205, 207, 209, 211, 213, 215, 217, 219, 221, 223, 225, 227, 229, 231, 233, 235, 237, 239, 241, 243, 245, 247, 249, 251, 253, 255, 257, 259, 261, 263, 265, 267, 269
Offset: 1

Views

Author

Stefano Spezia, Jul 07 2025

Keywords

Examples

			263 is a term since 632 = 158*4 is divisible by 4.
		

Crossrefs

Similar sequences for k=1..9: A001477, A273892, A008585, this sequence, A217398, A385701, A385702, A385703, A008591.

Programs

  • Mathematica
    Select[Range[0,270],Divisible[FromDigits[RotateLeft[IntegerDigits[#]]],4] &]
  • PARI
    isok(k) = if (k==0, return(1)); my(d=digits(k), v = vector(#d-1, i, d[i+1])); v = concat(v, d[1]); fromdigits(v) % 4 == 0; \\ Michel Marcus, Jul 08 2025
    
  • Python
    def ok(n): return int((s:=str(n))[1:]+s[0])%4 == 0
    print([k for k in range(270) if ok(k)]) # Michael S. Branicky, Jul 08 2025

A385701 Numbers such that when the leftmost digit is moved to the unit's place the result is divisible by 6.

Original entry on oeis.org

0, 6, 21, 24, 27, 42, 45, 48, 60, 63, 66, 69, 81, 84, 87, 201, 204, 207, 210, 213, 216, 219, 222, 225, 228, 231, 234, 237, 240, 243, 246, 249, 252, 255, 258, 261, 264, 267, 270, 273, 276, 279, 282, 285, 288, 291, 294, 297, 402, 405, 408, 411, 414, 417, 420, 423, 426, 429
Offset: 1

Views

Author

Stefano Spezia, Jul 07 2025

Keywords

Examples

			426 is a term since 264 = 44*6 is divisible by 6.
		

Crossrefs

Similar sequences for k=1..9: A001477, A273892, A008585, A385700, A217398, this sequence, A385702, A385703, A008591.

Programs

  • Mathematica
    Select[Range[0,430],Divisible[FromDigits[RotateLeft[IntegerDigits[#]]],6] &]
  • PARI
    isok(k) = if (k==0, return(1)); my(d=digits(k), v = vector(#d-1, i, d[i+1])); v = concat(v, d[1]); fromdigits(v) % 6 == 0; \\ Michel Marcus, Jul 08 2025
    
  • Python
    def ok(n): return int((s:=str(n))[1:]+s[0])%6 == 0
    print([k for k in range(430) if ok(k)]) # Michael S. Branicky, Jul 08 2025
Showing 1-10 of 14 results. Next