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.

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.
		

Crossrefs

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

Programs

A246044 Monoprimatic permutable primes: Decimal prime numbers whose digits cannot be rearranged to form another prime number. No leading zeros allowed.

Original entry on oeis.org

2, 3, 5, 7, 11, 19, 23, 29, 41, 43, 47, 53, 59, 61, 67, 83, 89, 101, 103, 109, 151, 211, 223, 227, 229, 233, 257, 263, 269, 307, 353, 383, 401, 409, 431, 433, 443, 449, 487, 499, 503, 509, 523, 541, 557, 599, 601, 607, 661, 677, 773, 809, 827, 829, 853, 859, 881, 883, 887, 929, 997, 1447, 1451, 1481, 2003, 2017, 2029, 2087
Offset: 1

Views

Author

Andreas Boe, Aug 23 2014

Keywords

Examples

			859 -> 589 (composite), 598 (even), 859 (prime), 895 (composite), 958 (even), 985 (composite) -> conclusion: one prime number.
		

Crossrefs

Cf. A245808 (monoprimatic permutable numbers)
Cf. A246043 (biprimatic permutable numbers), A246045 (biprimatic permutable primes).

Programs

  • Mathematica
    mppQ[n_]:=Total[Boole[PrimeQ[Select[FromDigits/@Permutations[IntegerDigits[n]],IntegerLength[ #] == IntegerLength[ n]&]]]] ==1; Select[Prime[Range[500]],mppQ] (* Harvey P. Dale, Dec 06 2021 *)
  • Python
    from itertools import permutations
    from sympy import prime, isprime
    A246044 = []
    for n in range(1,10**6):
        p = prime(n)
        for x in permutations(str(p)):
            if x[0] != '0':
                p2 = int(''.join(x))
                if p2 != p and isprime(p2):
                    break
        else:
            A246044.append(p) # Chai Wah Wu, Aug 27 2014

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.
		

Crossrefs

A245808: Monoprimatic permutable numbers
A246044: Monoprimatic permutable primes
A246043: Biprimatic permutable numbers

A248010 Non-primatic permutable numbers: All permutations of the number's digits except the ones resulting in leading zeros are nonprimes.

Original entry on oeis.org

1, 4, 6, 8, 9, 10, 12, 15, 18, 20, 21, 22, 24, 25, 26, 27, 28, 30, 33, 36, 39, 40, 42, 44, 45, 46, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 75, 77, 78, 80, 81, 82, 84, 85, 86, 87, 88, 90, 93, 94, 96, 99, 100, 102, 105, 108, 111, 114, 116, 117, 120, 122, 123, 126, 129, 132, 135, 138, 141, 144, 147
Offset: 1

Views

Author

Andreas Boe, Sep 29 2014

Keywords

Comments

This sequence differs slightly from "absolute composite numbers". 30 is not an absolute composite since 03 is counted as a prime, but in this sequence permutations with leading zeros are disqualified as viable permutations.

Examples

			7000 qualifies since it is a composite and the only allowed permutation of its four digits.
		

Crossrefs

Absolute composites: A067012, A067013.
Monoprimatic permutable numbers: A245808.
Biprimatic permutable numbers: A246043.
Showing 1-4 of 4 results.