A177061 Primes p formed from single-digit primes only, each used at most once.

2, 3, 5, 7, 23, 37, 53, 73, 257, 523, 2357, 2753, 3257, 3527, 5237, 5273, 7253, 7523

Offset

1,1

Comments

List of (p,i): (2,1), (3,2), (5,3), (7,4), (23,9), (37,12), (53,16), (73,21), (257,55), (523,99), (2357,350), (2753,402), (3257,460), (3527,492), (5237,697), (5273, 699), (7253,928), (7523,953).

There are exactly eight primes whose digits are primes in strictly increasing order: 2, 3, 5, 7, 23, 37, 257, 2357. - James C. McMahon, Jul 04 2023

There are exactly six primes whose digits are primes in strictly decreasing order: 2, 3, 5, 7, 53, 73. - James C. McMahon, Aug 09 2023

References

E. I. Ignatjew, Mathematische Spielereien, Urania Verlag Leipzig/Jena/Berlin 1982

Links

Table of n, a(n) for n=1..18.

Example

3//7 = 37 = prime(12) is the 6th term.
2//3//5//7 = 2357 = prime(350) is the 11th term
p = 7//5//2//3 = 7523 = prime(953) = A033548(59) is the last term.

Mathematica

Select[FromDigits/@Flatten[Permutations/@Subsets[{2, 3, 5, 7}], 1], PrimeQ]// Union (* Harvey P. Dale, Sep 08 2021 *)

Prog

(PARI) isok(p) = {my(d = digits(p)); if (#d == #Set(d) && vecmin(apply(isprime, d)) == 1, return (1)); return(0); }
lista() = {forprime(p=1, 100000, if (isok(p), print1(p, ", ")); ); } \\ Michel Marcus, Aug 07 2020

Crossrefs

Cf. A000040, A168349, A168385, A347612

Sequence in context: A096148 A211681 A124674 * A020994 A085823 A284060

Adjacent sequences: A177058 A177059 A177060 * A177062 A177063 A177064

Keyword

easy,base,fini,full,nonn

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), May 02 2010

Extensions

Edited by Assoc. Eds. OEIS, May 09 2010

Missing term 5273 added by Eren Donmez, Aug 07 2020

Cross reference added by Harvey P. Dale, Sep 09 2021

Status

approved