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 1-3 of 3 results.

A245808 Monoprimatic permutable numbers: Numbers whose decimal digits can be arranged to form exactly one prime number. No leading zeros.

Original entry on oeis.org

2, 3, 5, 7, 11, 14, 16, 19, 23, 29, 32, 34, 35, 38, 41, 43, 47, 53, 59, 61, 67, 74, 76, 83, 89, 91, 92, 95, 98, 101, 103, 104, 106, 109, 110, 112, 115, 121, 130, 134, 140, 143, 145, 151, 154, 160, 166, 188, 190, 211, 223, 227, 229, 232, 233, 235, 236, 253, 257, 263, 269, 272, 275, 278, 287, 289, 292
Offset: 1

Views

Author

Andreas Boe, Aug 22 2014

Keywords

Comments

The sequence takes a surprisingly large number of computations to generate since the number of permutations rises quickly with the number of digits. Generating the sequence is an excellent programming exercise since there are several approaches to calculate the same sequence. Regardless of approach, there are many ways to optimize the algorithms, so the sequence would be a good choice of assignment for a contest between programmers. The assignment also has some pitfalls, mainly due to the problem of how to handle leading zeros.
The sequence was originally explored for the development of two puzzles found in the science fiction novel "The Right Left" by Andreas Boe.

Examples

			190 -> 019 (forbidden), 091 (forbidden), 109 (prime), 190 (even), 901 (composite), 910 (even) -> Conclusion: One prime number.

References

  • Andreas Boe, The Right Left, Amazon books, 2014.

Links

Crossrefs

Cf. A246044 (Monoprimatic permutable primes), A246043 (Biprimatic permutable numbers), A246045 (Biprimatic permutable primes).

A246043 Biprimatic permutable numbers: Decimal numbers whose digits can be arranged to form exactly two prime numbers. No leading zeros.

Original entry on oeis.org

13, 17, 31, 37, 71, 73, 79, 97, 107, 118, 119, 124, 125, 127, 128, 133, 139, 142, 146, 152, 164, 169, 170, 172, 181, 182, 191, 193, 196, 214, 215, 217, 218, 238, 239, 241, 251, 271, 277, 281, 283, 293, 313, 319, 328, 329, 331, 346, 347, 349, 356, 364, 365, 367, 368, 374, 376, 382, 386, 391, 392, 394, 412, 416, 421, 436, 437
Offset: 1

Views

Author

Andreas Boe, Aug 23 2014

Keywords

Comments

In base ten these numbers can be said to have a prime twin made up of the same digits.

Examples

			170 -> 017 (forbidden), 071 (forbidden), 107 (prime), 170 (even), 701 (prime), 710 (even) -> conclusion: Two prime numbers.

Links

Crossrefs

A245808: Monoprimatic permutable numbers
A246044: Monoprimatic permutable primes
A246045: Biprimatic permutable primes

Programs

A246045 Biprimatic permutable primes: prime numbers whose digits can be rearranged to form exactly one other prime number. No leading zeros allowed.

Original entry on oeis.org

13, 17, 31, 37, 71, 73, 79, 97, 107, 127, 139, 181, 191, 193, 239, 241, 251, 271, 277, 281, 283, 293, 313, 331, 347, 349, 367, 421, 439, 457, 461, 463, 467, 479, 521, 547, 563, 569, 577, 587, 619, 641, 643, 647, 653, 659, 673, 683, 691, 701, 709, 727, 743, 757, 769, 787, 797, 811, 821, 823, 857, 863, 877, 907, 911, 947, 967
Offset: 1

Views

Author

Andreas Boe, Aug 23 2014

Keywords

Comments

In base ten the numbers can be said to have a prime twin made up of the same digits.

Examples

			709 -> 079 (forbidden), 097 (forbidden), 709 (prime), 790 (even), 907 (prime), 970 (even) -> conclusion: Two primes.

Links

Crossrefs

A245808: Monoprimatic permutable numbers
A246044: Monoprimatic permutable primes
A246043: Biprimatic permutable numbers
Showing 1-3 of 3 results.

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

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