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

A083852 Decimal palindromes that are multiples of 11.

Original entry on oeis.org

0, 11, 22, 33, 44, 55, 66, 77, 88, 99, 121, 242, 363, 484, 616, 737, 858, 979, 1001, 1111, 1221, 1331, 1441, 1551, 1661, 1771, 1881, 1991, 2002, 2112, 2222, 2332, 2442, 2552, 2662, 2772, 2882, 2992, 3003, 3113, 3223, 3333, 3443, 3553, 3663, 3773, 3883, 3993, 4004
Offset: 1

Views

Author

Reinhard Zumkeller, May 06 2003

Keywords

Comments

A083850(a(n))>0; palindromes with even length are terms.

Crossrefs

Programs

  • Mathematica
    Select[Range[0, 5500, 11], PalindromeQ] (* Paolo Xausa, Jul 07 2025 *)
  • PARI
    forstep(k=0, 10^5, 11, d=digits(k); d==Vecrev(d) && print1(k, ", ")) \\ Jeppe Stig Nielsen, May 08 2020

A043040 Numbers that are palindromic and divisible by 5.

Original entry on oeis.org

0, 5, 55, 505, 515, 525, 535, 545, 555, 565, 575, 585, 595, 5005, 5115, 5225, 5335, 5445, 5555, 5665, 5775, 5885, 5995, 50005, 50105, 50205, 50305, 50405, 50505, 50605, 50705, 50805, 50905, 51015, 51115, 51215, 51315, 51415, 51515, 51615, 51715, 51815, 51915
Offset: 1

Views

Author

Keywords

Comments

Or, 0 and numbers that are palindromic and begin with 5.

Crossrefs

Programs

  • Mathematica
    palQ[n_Integer, base_Integer] := Module[{idn = IntegerDigits[n, base]}, idn == Reverse[idn]];
    Join[{0},Select[Range[5,100000,5], IntegerDigits[#][[1]] == 5 && palQ[#, 10] &]] (* T. D. Noe, Mar 12 2013 *)
    Select[5*Range[0,11000],IntegerDigits[#]==Reverse[IntegerDigits[#]]&] (* Harvey P. Dale, Nov 29 2015 *)

Extensions

Edited to include a(1) = 0 by Paolo Xausa, Jul 07 2025

A045642 Palindromic and divisible by 7.

Original entry on oeis.org

0, 7, 77, 161, 252, 343, 434, 525, 595, 616, 686, 707, 777, 868, 959, 1001, 1771, 2002, 2772, 3003, 3773, 4004, 4774, 5005, 5775, 6006, 6776, 7007, 7777, 8008, 8778, 9009, 9779, 10101, 10801, 11011, 11711, 12621, 13531, 14441, 15351, 16261, 16961
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[0, 21000, 7], PalindromeQ] (* Paolo Xausa, Jul 06 2025 *)

Extensions

a(1) = 0 prepended by Paolo Xausa, Jul 07 2025

A045638 Palindromic and divisible by 3.

Original entry on oeis.org

0, 3, 6, 9, 33, 66, 99, 111, 141, 171, 222, 252, 282, 303, 333, 363, 393, 414, 444, 474, 525, 555, 585, 606, 636, 666, 696, 717, 747, 777, 828, 858, 888, 909, 939, 969, 999, 1221, 1551, 1881, 2112, 2442, 2772, 3003, 3333, 3663, 3993, 4224, 4554, 4884, 5115
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[0,5500,3],PalindromeQ] (* Harvey P. Dale, Apr 14 2023 *)

Extensions

Edited to include a(1) = 0 by Paolo Xausa, Jul 07 2025

A045639 Palindromic and divisible by 4.

Original entry on oeis.org

0, 4, 8, 44, 88, 212, 232, 252, 272, 292, 404, 424, 444, 464, 484, 616, 636, 656, 676, 696, 808, 828, 848, 868, 888, 2112, 2332, 2552, 2772, 2992, 4004, 4224, 4444, 4664, 4884, 6116, 6336, 6556, 6776, 6996, 8008, 8228, 8448, 8668, 8888, 21012, 21112, 21212
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    palQ[n_]:=Module[{idn=IntegerDigits[n]},idn==Reverse[idn]]; Select[4*Range[0, 6000],palQ]  (* Harvey P. Dale, Jan 30 2011 *)

Extensions

Edited to include a(1) = 0 by Paolo Xausa, Jul 07 2025

A045643 Palindromic and divisible by 8.

Original entry on oeis.org

0, 8, 88, 232, 272, 424, 464, 616, 656, 696, 808, 848, 888, 2112, 2552, 2992, 4224, 4664, 6336, 6776, 8008, 8448, 8888, 21112, 21312, 21512, 21712, 21912, 23032, 23232, 23432, 23632, 23832, 25152, 25352, 25552, 25752, 25952, 27072, 27272, 27472
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    palQ[n_]:=Module[{idn=IntegerDigits[n]},idn==Reverse[idn]];Select[ 8Range[0,3500],palQ] (* Harvey P. Dale, Jun 06 2011 *)
    Select[8*Range[0, 3500],PalindromeQ] (* Harvey P. Dale, Feb 17 2023 *)

Extensions

Edited to include a(1) = 0 by Paolo Xausa, Jul 07 2025

A045644 Palindromic and divisible by 9.

Original entry on oeis.org

0, 9, 99, 171, 252, 333, 414, 585, 666, 747, 828, 909, 999, 1881, 2772, 3663, 4554, 5445, 6336, 7227, 8118, 9009, 9999, 10701, 11511, 12321, 13131, 14841, 15651, 16461, 17271, 18081, 18981, 19791, 20502, 21312, 22122, 23832, 24642, 25452, 26262
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    Select[9*Range[0,3000],PalindromeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Mar 30 2020 *)

Extensions

Edited to include a(1) = 0 by Paolo Xausa, Jul 07 2025

A029950 Odd palindromes.

Original entry on oeis.org

1, 3, 5, 7, 9, 11, 33, 55, 77, 99, 101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 303, 313, 323, 333, 343, 353, 363, 373, 383, 393, 505, 515, 525, 535, 545, 555, 565, 575, 585, 595, 707, 717, 727, 737, 747, 757, 767, 777, 787, 797, 909, 919, 929, 939, 949
Offset: 1

Views

Author

Keywords

Comments

There are more odd palindromes (A328332) less than 10^K than even palindromes (A328333) because odd palindromes begin with 1, 3, 5, 7 or 9 while even palindromes begin only with 2, 4, 6 or 8. - Bernard Schott, Oct 24 2019

Crossrefs

Subsequence of A002113.
Cf. A029951 (even palindromes), A328332, A328333.

Programs

  • Mathematica
    palindromicQ[n_,b_:10]:=TrueQ[IntegerDigits[n, b]==Reverse[IntegerDigits[n, b]]];Select[Range[1, 10^4, 2], palindromicQ[#]&&Plus@@Drop[DigitCount[#], {1, 10, 1}]==0&] (* Vincenzo Librandi, Feb 07 2014 *)
    Select[Range[1,949,2],PalindromeQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 15 2017 *)
  • PARI
    lista(nn) = {forstep(n=1, nn, 2, if (is_A002113(n), print1(n, ", ")));} \\ Michel Marcus, Feb 06 2014

Extensions

Offset set to 1 and more terms from Michel Marcus, Feb 06 2014

A045641 Palindromes that are divisible by 6.

Original entry on oeis.org

0, 6, 66, 222, 252, 282, 414, 444, 474, 606, 636, 666, 696, 828, 858, 888, 2112, 2442, 2772, 4224, 4554, 4884, 6006, 6336, 6666, 6996, 8118, 8448, 8778, 20202, 20502, 20802, 21012, 21312, 21612, 21912, 22122, 22422, 22722, 23232, 23532, 23832
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Range[0,30000,6], PalindromeQ] (* Paolo Xausa, Jul 06 2025 *)

A328333 Expansion of (1 + 4*x - 6*x^2) / ((1 - x) * (1 - 10*x^2)).

Original entry on oeis.org

1, 5, 9, 49, 89, 489, 889, 4889, 8889, 48889, 88889, 488889, 888889, 4888889, 8888889, 48888889, 88888889, 488888889, 888888889, 4888888889, 8888888889, 48888888889, 88888888889, 488888888889, 888888888889, 4888888888889, 8888888888889, 48888888888889, 88888888888889
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 12 2019

Keywords

Comments

Number of even palindromes < 10^n.

Crossrefs

Programs

  • Mathematica
    nmax = 28; CoefficientList[Series[(1 + 4 x - 6 x^2)/((1 - x) (1 - 10 x^2)), {x, 0, nmax}], x]
    LinearRecurrence[{1, 10, -10}, {1, 5, 9}, 29]
  • PARI
    Vec((1 + 4*x - 6*x^2) / ((1 - x) * (1 - 10*x^2)) + O(x^30)) \\ Michel Marcus, Oct 13 2019
Showing 1-10 of 12 results. Next