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.

A335314 Full autoinsertable of reversed multidigit primes are such primes that remain prime after all the possible internal autoinsertions of the reversed prime, one at a time.

Original entry on oeis.org

127, 131, 149, 163, 191, 347, 383, 457, 463, 479, 521, 569, 571, 613, 643, 653, 659, 739, 757, 797, 941, 40471, 49991, 79627, 81869, 83407, 5916623
Offset: 1

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Author

Carlos Rivera, Jun 01 2020

Keywords

Comments

If the prime has K digits all the possible internal autoinsertions are K-1.
Supposed to have only a finite quantity of terms.
If it exists, the next term a(28) is > 2^32.

Examples

			Example: 127 generates 2 primes 1'721'27 and 12'721'7
Example: 5916623 generates 6 primes: 5'3266195'916623, 59'3266195'16623, 591'3266195'6623, 5916'3266195'623, 59166'3266195'23, 591662'3266195'3
		

Crossrefs

Cf. A335271.

Programs

  • PARI
    forprime(p=11, 10^8, my(v=digits(p), d=#v, f=1); for(i=1, d-1, my(t=concat(concat(v[1..i], Vecrev(v)), v[i+1..d]), q=fromdigits(t)); if(!isprime(q), f=0; break)); if(f, print1(p, ", "))) \\ Hugo Pfoertner, Jun 01 2020