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 1-4 of 4 results.

A192137 Numbers m such that their concatenation of prime divisors are palindromic numbers.

Original entry on oeis.org

2, 3, 4, 5, 7, 8, 9, 11, 16, 25, 27, 32, 39, 49, 64, 69, 81, 101, 117, 119, 121, 125, 128, 129, 131, 151, 159, 181, 191, 207, 219, 243, 249, 256, 259, 313, 329, 339, 343, 351, 353
Offset: 1

Views

Author

Jaroslav Krizek, Jun 24 2011

Keywords

Comments

The corresponding values of palindromic concatenation in A192138. Superset of A002385 (palindromic primes), A192139 and A192140.

Examples

			Concatenation of prime divisors of 39 = 3 * 13 is 313 (palindromic number).

Links

Crossrefs

Cf. A002113, A002385, A084317, A084092, A192138, A192139, A192140, A192141.

Programs

  • Mathematica
    Select[Range[2,500],PalindromeQ[FromDigits[Flatten[IntegerDigits/@ FactorInteger[ #][[All,1]]]]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 02 2017 *)

A192139 Powers p^m, m >= 0, of palindromic primes p (A002385).

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 8, 9, 11, 16, 25, 27, 32, 49, 64, 81, 101, 121, 125, 128, 131, 151, 181, 191, 243, 256, 313, 343, 353, 373, 383, 512, 625, 727, 729, 757, 787, 797, 919, 929, 1024, 1331, 2048, 2187, 2401, 3125, 4096, 6561, 8192, 10201, 10301, 10501, 10601, 11311, 11411, 12421, 12721
Offset: 1

Views

Author

Jaroslav Krizek, Jun 24 2011

Keywords

Comments

Superset of A002385 and A084092. Subset of A192137.

Links

Crossrefs

Cf. A002113, A002385, A084317, A084092, A192137, A192138, A192140, A192141.

Programs

Extensions

Missing term 625 inserted and more terms added by M. F. Hasler, May 11 2015

A192138 Palindromic concatenation of prime divisors of numbers from A192137.

Original entry on oeis.org

2, 3, 2, 5, 7, 2, 3, 11, 2, 5, 3, 2, 313, 7, 2, 323, 3, 101, 313, 717, 11, 5, 2, 343, 131, 151, 353, 181, 191, 323, 373, 3, 383, 2, 737, 313, 747, 3113, 7, 313, 353, 373, 383, 343, 1331, 31113, 767, 353, 313, 2, 323, 5, 373, 3223, 797, 727, 3, 383, 757, 787, 3553
Offset: 1

Views

Author

Jaroslav Krizek, Jun 24 2011

Keywords

Examples

			a(13) = 313 because A192137(13) = 39 = 3 * 13.

Crossrefs

Cf. A002113, A002385, A084317, A084092, A192137, A192139, A192140, A192141.

Programs

  • Mathematica
    f[n_] := FromDigits[Flatten[IntegerDigits /@ FactorInteger[n][[;; , 1]]]]; Select[f /@ Range[2, 1900], PalindromeQ] (* Amiram Eldar, Aug 06 2024 *)

Extensions

More terms from Amiram Eldar, Aug 06 2024

A192140 Palindromic numbers m such that their concatenation of prime divisors are also palindromic numbers.

Original entry on oeis.org

2, 3, 4, 5, 7, 8, 9, 11, 101, 121, 131, 151, 181, 191, 313, 343, 353, 373, 383, 727, 747, 757, 787, 797, 919, 929, 1331, 10001, 10201, 10301, 10501, 10601, 11311, 11411, 12421, 12721, 12821, 13331, 13831, 13931, 14341, 14641, 14741, 15451, 15551, 16061, 16361
Offset: 1

Views

Author

Jaroslav Krizek, Jun 24 2011

Keywords

Comments

The corresponding values of palindromic concatenation in A192141.
Superset of A002385 (palindromic primes) and A084092 (prime power decimal palindromes).
Subset of A002113 (palindromic numbers) and A192137.

Examples

			Concatenation of prime divisors of number 747 = 3^2 * 83 is 383 (palindromic number).

Crossrefs

Cf. A002113, A002385, A084317, A084092, A192137, A192138, A192139, A192141.

Programs

  • Mathematica
    f[n_] := FromDigits[Flatten[IntegerDigits /@ FactorInteger[n][[;; , 1]]]]; Select[Range[2, 20000], And @@ (PalindromeQ /@ {#, f[#]}) &] (* Amiram Eldar, Aug 06 2024 *)

Extensions

More terms from Amiram Eldar, Aug 06 2024
Showing 1-4 of 4 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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