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 10 results.

A045640 Duplicate of A043040.

Original entry on oeis.org

5, 55, 505, 515, 525, 535, 545, 555, 565, 575, 585, 595, 5005, 5115, 5225
Offset: 1

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Author

Keywords

A029951 Even palindromes.

Original entry on oeis.org

0, 2, 4, 6, 8, 22, 44, 66, 88, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 404, 414, 424, 434, 444, 454, 464, 474, 484, 494, 606, 616, 626, 636, 646, 656, 666, 676, 686, 696, 808, 818, 828, 838, 848, 858, 868, 878, 888, 898, 2002, 2112, 2222
Offset: 1

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Author

Keywords

Crossrefs

Cf. A002113 (superset), A062287 (subset), A367807 (halved).

Programs

  • Mathematica
    palindromicQ[n_, b_:10] := TrueQ[IntegerDigits[n, b] == Reverse[IntegerDigits[n, b]]]; Select[Range[2, 10^4, 2], palindromicQ[#] &] (* Alonso del Arte, Feb 23 2012 *)
    Select[Range[0, 2222, 2], PalindromeQ] (* Michael De Vlieger, May 12 2017, Version 10.3 *)

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

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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

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

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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

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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

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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

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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

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 *)

A337184 Numbers divisible by their first digit and their last digit.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 15, 22, 24, 33, 36, 44, 48, 55, 66, 77, 88, 99, 101, 102, 104, 105, 111, 112, 115, 121, 122, 123, 124, 125, 126, 128, 131, 132, 135, 141, 142, 144, 145, 147, 151, 152, 153, 155, 156, 161, 162, 164, 165, 168, 171, 172, 175, 181, 182
Offset: 1

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Author

Bernard Schott, Jan 29 2021

Keywords

Comments

The first 23 terms are the same first 23 terms of A034838 then a(24) = 101 while A034838(24) = 111.
Terms of A034709 beginning with 1 and terms of A034837 ending with 1 are terms.
All positive repdigits (A010785) are terms.
There are infinitely many terms m for any of the 53 pairs (first digit, last digit) of m described below: when m begins with {1, 3, 7, 9} then m ends with any digit from 1 to 9; when m begins with {2, 4, 6, 8}, then m must also end with {2, 4, 6, 8}; to finish, when m begins with 5, m must only end with 5. - Metin Sariyar, Jan 29 2021

Crossrefs

Intersection of A034709 and A034837.
Subsequences: A010785\{0}, A034838, A043037, A043040, A208259, A066622.
Cf. A139138.

Programs

  • Mathematica
    Select[Range[175], Mod[#, 10] > 0 && And @@ Divisible[#, IntegerDigits[#][[{1, -1}]]] &] (* Amiram Eldar, Jan 29 2021 *)
  • PARI
    is(n) = n%10>0 && n%(n%10)==0 && n % (n\10^logint(n,10)) == 0 \\ David A. Corneth, Jan 29 2021
  • Python
    def ok(n): s = str(n); return s[-1] != '0' and n%int(s[0])+n%int(s[-1]) == 0
    print([m for m in range(180) if ok(m)]) # Michael S. Branicky, Jan 29 2021
    

Formula

(10n-9)/9 <= a(n) < 45n. (I believe the liminf of a(n)/n is 3.18... and the limsup is 6.18....) - Charles R Greathouse IV, Nov 26 2024
Conjecture: 3n < a(n) < 7n for n > 75. - Charles R Greathouse IV, Dec 02 2024
Showing 1-10 of 10 results.