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.

A237438 Double Hex-primes: let f(n) = A102489(n); then sequence lists primes p such that f(p) and f(f(p)) are also primes.

Original entry on oeis.org

2, 3, 5, 7, 11, 43, 47, 53, 59, 61, 89, 97, 101, 139, 151, 167, 199, 241, 251, 257, 269, 281, 337, 373, 443, 557, 599, 607, 647, 653, 829, 971, 1051, 1093, 1163, 1223, 1279, 1327, 1433, 1459, 1499, 1549, 1583, 1597, 1607
Offset: 1

Views

Author

Andreas Boe, Feb 07 2014

Keywords

Comments

This sequence is a subset of A103144.

Examples

			Dec61=prime -> Hex61=Dec97=prime -> Hex97=Dec151=prime.

Links

Crossrefs

Cf. A102489.
Cf. A103144 (Hex-primes), A237439 (Triple Hex-primes), A237440 (Quadruple Hex-primes), A237441 (Quintuple Hex-primes).

A237440 Quadruple Hex-primes: let f(n) = A102489(n); then sequence lists primes p such that f(p), f(f(p)). f(f(f(p))) and f(f(f(f(p)))) are also primes.

Original entry on oeis.org

2, 3, 5, 7, 61, 97, 101, 257, 2531, 4783, 5683, 6317, 8963, 9463, 9497, 11593, 15683, 18757, 23687, 26251, 29611, 31271, 36011, 45497, 45979, 46853, 54869, 73379, 92557, 93761, 104173, 107857, 107981, 121607, 134047, 192091, 196853, 236729, 285599, 310081
Offset: 1

Views

Author

Andreas Boe, Feb 07 2014

Keywords

Comments

The sequence is a subset of sequences A103144, A237438, and A237439.

Examples

			Dec61=prime -> Hex61=Dec97=prime -> Hex97=Dec151=prime -> Hex151=Dec337=prime -> Hex337=Dec823=prime.

Links

Crossrefs

Cf. A102489.
Cf. A103144 (Hex-primes), A237438 (Double Hex-primes), A237439 (Triple Hex-primes), A237441 (Quintuple Hex-primes).

Programs

  • Mathematica
    qhpQ[n_]:=AllTrue[Rest[NestList[FromDigits[IntegerDigits[#],16]&,n,4]], PrimeQ]; Select[Prime[Range[27000]],qhpQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Mar 13 2016 *)
  • PARI
    isok(p)= isprime(p) && isprime(p=hd(p)) && isprime(p=hd(p)) && isprime(p=hd(p)) && isprime(p=hd(p)); \\ Michel Marcus, Feb 09 2014

Extensions

More terms from Michel Marcus, Feb 09 2014

A237441 Quintuple Hex-primes: let f(n) = A102489(n); then sequence lists primes p such that f(p), f(f(p)), f(f(f(p))), f(f(f(f(p)))) and f(f(f(f(f(p))))) are also primes.

Original entry on oeis.org

2, 3, 5, 7, 61, 101, 196853, 516151, 548239, 568627, 595039, 603833, 648887, 1996223, 2086907, 2487227, 3322757, 3711343, 4385137, 5226049, 5288929, 5853241, 8792039, 8796187, 8982191, 10203203, 12640297, 12664129, 12845561, 13156267, 13437481, 14342431
Offset: 1

Views

Author

Andreas Boe, Feb 07 2014

Keywords

Comments

The sequence is a subset of A103144, A237438, A237439 and A237440

Examples

			Dec61=prime -> Hex61=Dec97=prime -> Hex97=Dec151=prime -> Hex151=Dec337=prime -> Hex337=Dec823=prime -> Hex823=Dec2083=prime.

Crossrefs

Cf. A102489
Cf. A103144(Hex-primes), A237438(Double Hex-primes), A237439(Triple Hex-primes), A237440(Quadruple Hex-primes).

Programs

  • PARI
    hd(n) = my(d = digits(n)); sum(i=1, #d, 16^(i-1)*d[#d-i+1]);
isok(p) = isprime(p) && isprime(p=hd(p)) && isprime(p=hd(p)) && isprime(p=hd(p)) && isprime(p=hd(p)) && isprime(p=hd(p)); \\ Michel Marcus, Feb 08 2014

Extensions

More terms from Michel Marcus, Feb 08 2014
Showing 1-3 of 3 results.

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

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